in a late victory scenario, Germany is assured to lose some colonies, particularly South West Africa and East Africa, as there is no way they can force the British to hand them back, nor they can seriously threaten the UK elsewhere; this unless the Germans manage to somehow entrap a large portion of the British armies in France, which may alter the political calculus.
We had a discussion about this exact point on another thread a while ago. To recycle my post from there:
Britain would've found itself confronted with a contradiction between it's basic two war goals:
1.) Prevent German domination on the continent.
2.) Seize German colonies.
And as it stands, Britain needs a strong France and a friendly Belgium way more than Kenya or Togoland. From a grand-strategic point of view, a German-dominated Europe and a broken France directly threatened Britain's status as a great power. Not immediately, no, a German invasion of Britain is not on the table during WW1. But who knows what would be 20 years later. With the ressources of all of Europe at it's disposal, the Germans might be able to win a new naval arms race with Britain. And then what? Who is going to stop them, if France remains permanently crippled (as the envisioned reparations would've ensured)? And even if an invasion would've remained unfeasable for the forseeable future – Dover is in range of German long-range artillery. The German navy is based directly in the channel. We saw how German submarine warfare disrupted shipping to and from Britain during both world wars in OTL – all of this would pale in comparison to a second great war in this scenario, with Germany not disarmed after WW1 but, on the contrary, in possesion of a much larger ressource base.
And that's not even the full story. There are more immediate concerns for Britain which would make them want to agree to such a peace aswell. With the fighting on the continent basically over, the Germans can drastically increase it's naval production. During WW1 Germany had the second largest navy in the entire world and during WW2 Germany had a relatively small navy. Still, during WW2 the German navy proved to be a lot more effective. The reason for this is the fact that during WW1 Germany lacked good bases to operate against Britain from, they were hemmed in behind the Norway-Faroes-Orkneys Gap and the Dover Strait. With it's victory over France however, Germany would've been able to take control of the French channel and atlantic ports. Combined with the fact that the French navy is out of the war after the German victory on the western front and the innevitable armistice, it is safe to say that British shipping suffers big time. Furthermore, with France out of the war and victory in the east archieved, the Germans can focus on supporting the Ottoman war effort in the Middle East. Earlier or later, the Suez channel would fall. And suddenly it's Britain that faces a serious supply problem – such a situation is unbearable for the British.
Now to the Germans: Their situation would've definetly been precarious, but not as much as it may seem at first glance. With the French navy out of the war and with German control over the French ports, Britain would have to seriously enlarge it's blockade – combine this with the aforementioned fact regarding Germany's ability to ramp up naval production, and it becomes pretty clear that the British blockade would've been rendered ineffective. Even if we're talking about a late victory scenario here and the US has entered the war on the Entente side, the American navy was small in comparison to the British, German and even French navies. And even apart from the fact that the blockade is rendered ineffective, things are not nearly as grim for Germany supply wise (regarding the military aswell as the civilian population) as it had been during the turnip winter OTL. Ukraine is under German control. In an early victory scenario, Russia is not in the midst of a civil war and is forced by treaty and by economic neccesity to resume trade with Germany. And in a late victory scenario, much of the Caucasus is pro-German. Even in OTL, the food situation had improved during the summer of 1918 compared to the summer of 1917. And if, even after all of this, the supply situation is still not sufficient, well, foodstuff can be requisitioned from all over German-occupied Europe, including France.
In any case, the war can not continue for longer than an additional year. War-weariness was growing increasingly widespread and in turn lead to revolutionary sentiment. Many people don't realize how close all parties involved were to a revolution in 1918. In OTL, revolutions took place in British Ireland, in Ottoman Arabia, in Russia, in Germany, and in slavic Austria-Hungary. The military rank-and-file was far from immune against revolutionary sentiment either – the soldiers had played a crucial role in both Russian revolutions of 1917, there had been massive mutinies among the ranks of the French army in 1917, and the German November revolution of 1918 had been kickstarted by a sailors mutiny. The leadership on both sides needed peace badly and they needed it quickly. If the war was to continue for another year in this scenario, I could see war-weariness in Germany beeing temporarily alleviated by the victories in the field aswell as the improvement of the supply situation at home. Emphasis is placed on "temporarily" – the wave of nationalism and the relief about the improved supply situation would eventually give way to renewed war-weariness and revolutionary sentiment. The prospects for Britain are worse. After the fall of France, the war is lost. The increasingly difficult supply situation and the innevitable continuous military defeats at sea and on land would massively bolster war-weariness and revolutionary sentiment. By the end of 1919 both sides just can't fight anymore. If they decide to do so regardless, 1920s Europe ends up a lot redder.
However the whole question is rather scolastic in nature. We have seen that Britain needs a strong France and a friendly Belgium a lot more than the German colonies in Africa. Furthermore, in this scenario, the war is basically over allready. I've gone to great lengts to show that Britain can't beat Germany after the fall of France. The British political and military leadership is not dumb, they will accept the obvious fait accomply, and rather ealier than later. And why not? The worst Britain gets is a white peace. The Germans can't realistically force them to cede colonies or pay reparations. Britain has failed to archieve it's war goals and has lost around a million men in the field. Not more and not less. Why delay the innevitable and suffer more damage along the way?
Now, there remains one important question to answer: Would Germany even be willing to trade Belgium and eastern France against it's colonies in Africa, old and new?
Now, Belgium and all of France east of the Somme have way more strategic value compared to the African colonies. The seizure of these territories (combined with the envisioned heavy reparations) would've left France utterly broken. However, in terms of economic importance, Belgium and eastern France paled in comparison to what was to become German Mittelafrika. Many people don't seem to realize how crucial the colonial holdings were economically (and that's true for all great powers). They supplied the metropoles with resources and (just as importantly) they provided ample profitable investment opportunities for metropolitan monopolies. Colonies were key to avoid/postpone the overaccumulation of capital, and thus were essential in strengening the position of the metropolitan monopolies on the world market. The most important advantage a colonial holding has over an independent country, is that it can be closed off to foreign competition should the need arise. Direct control also has other advantages – the working class in the colonies can be exploited and oppressed a lot harsher than would've been ever possible in the metropoles. Cheap labour (partially organical due to the unequal development of capitalism, partially artificial due to harsher oppression) makes it possible to reap gigantic profits with relatively little capital. And the French and Belgians colonies in Africa were very rich in ressources.
In the decades preceding the war, Germany had had two main ambitions: 1.) Economic dominance over central Europe. 2.) The redivision of the colonies in Germany's favour. The concepts of Mitteleuropa and Mittelafrica were the logical consequence, and it's thus not surprising that they became Germany's two primary war goals in WW1.
And, had Germany defeated France and Russia, it could've realized both of them.
So, Britain would have to recognize German control over both the laters old colonies aswell as most of the French and Belgian colonies in Africa. Germany would, in turn, have to content itself with minor border corrections in France and Belgium, aswell as modest reparations.