I'm one of those people I suppose the OP mentions who focused on England itself in other recent threads, though I do think I said a fair amount about Europe in general and northwest Europe in particular as broad zones. It seems only logical that if the POD is the failure of the Hastings landing then we should be kind of Anglocentric in our gaming it out afterward since England itself is far and away the most drastically ATL place after all.
Leaving the most obvious stuff about England as given then...
I assume William failing to win in Kent probably means he himself is killed off along with a whole lot of the other Normans and Fleming lords he recruited, and thus Normandy and Flanders are in some chaos as an immediate knock on. I have not bothered to look up the contemporary King of France but I assume he was no Philip Augustus, but perhaps he would be immediately involved, attempting to weigh in on the hooraw in Normandy itself to try to tighten Paris's degree of control over the wayward duchy. If in fact the Bretons do seize opportunity to move in, that's another motive for any Parisian king to intervene because any territory Brittany captures is lost to France since Brittany I gather was not subordinated to Paris at all. The French king would thus be backing someone he hopes to have a stronger hold on than he had on William, but will accept only modest increases in control, or practically none at all, if it means the Bretons are held in check.
Vice versa--might not Harold of England come in to the mess himself? On one hand the English are exhausted, having fought off two major invasions in just a handful of weeks, so definitely not in 1066. Harold has got to consolidate his own control--but success against both Harald Hardarada and William the Bastard must be to his credit. Certainly the English have a major beef and score to settle with their trans-Channel neighbors who have treated them so badly; Denmark is after all farther off.
So English entanglement with the Continent might be a thing anyway, despite the lack of the very tight tie the Normans imposed OTL. Say the English decide to pony up some surplus force to ally with the Bretons (the English sure don't owe the King of France any favors either after all, nor the Holy Roman Emperor who was supposed to be the overlord of Flanders) with speculative agreements they can have pieces of Normandy and as much of Flanders as they can take on versus the Emperor--or even possibly in connivance with the Emperor, who might take the opportunity to engage with France on France's eastern and northern fronts while conceding the English some holdings on the mainland the better to get a stronger grip on Antwerp itself for instance.
Even if the English decide the smarter thing to do is remember their grievances but let things ride, as I said elsewhere, in the long run however much "purer" English Anglo-Saxon culture remains, it will evolve and in a manner that brings ties to the entire Continent in proportion to practical opportunity. I don't believe there is some sort of DNA based bias to tie the English northward to Scandinavia particularly; such ties are matters of opportunities that come up on both sides. Fundamentally, the Scandinavian north is peripheral and poor, albeit factors like controlling the strait into the Baltic can amount to quite a lot of wealth and revenue, which is why Denmark is pretty much guaranteed to dominate that sphere. Certainly there are pre-existing ties the Normans overwrote OTL, but they are as much negative as positive.
Broadly speaking, English opportunities and threats alike will come from south of Kent as much as north of it, and to the north the Low Countries are at least as important as Scandinavia. Meanwhile the center of High Middle Ages civilization in Western Europe is southward to the Mediterranean, Rome as center of Latin rite Catholicism, north Italy as the primary zone of incipient proto-capitalist manufacture and trade--the major overland branch of trade then runs far east through the Alps to the Rhine and Danube, but of course southern France is a major center as well. On the way to the Med by sea are the Iberian realms trying to oppose the generally divided realms of Muslim Andalusia. Nearer to hand, south of apparently politically potent but poor Brittany, are the same French domains that OTL anchored the Plantagenet empire--it is entirely possible various French lords will seek alliances piecemeal with the English, and the English, even if they shrewdly estimate the cost-effectiveness of aggressive conquest for the English crown on their own hook is rather poor, reciprocal relations with southwest French duchies and counties for both political and economic gain might suit them well. Certainly the crops of the French southwest Atlantic coast regions, such as Bordeaux wines, are reciprocal to what can be grown in England.
If England manages to fight off other opportunistic conquest attempts, as seems fairly likely, English people will still have a strong sheaf of interests drawing attention southward in Europe as much as northward. Whatever their relations with Flanders for instance, the straight east across the North Sea ties of developing industry there linking to England as wool producer and of other goods too I suppose will probably develop much the same, with the same effects and tensions.
What about the Crusades? A devotee of the Strong Butterfly would of course suppose everything is different in Europe a hundred years later, but I prefer to think of history as largely driven by deep currents and mere chaos as such is something we can disregard as much as we want to, being bound only to account for hard cause and effect knock ons. Messing up France in the decades after the ATL failed Conquest attempt would be largely damped down by the end of the century--a lot would be different in detail but perhaps the overall situation in France and Flanders (where most of the First Crusade came from) might be similar enough that the Pope's call for a volunteer armed pilgrimage to Jerusalem in aid of the recent alliance with the Eastern Emperor would be heeded much the same. If so, the lack of English involvement is not a deviation from OTL, whereas by the time a call for a Second Crusade rolls around, perhaps the English will participate much as the Plantagenets did OTL. Anyway, with or without English lords being involved, we can expect the Crusades to go largely as they did OTl, give or take random changes here and there.
England and English culture will evolve in lines fairly close to parallel to OTL overall I think, and by and large western Europe as well. The English language will remain more strongly Germanic but in fact the English showed a propensity to pick up words in their vocabularies pretty readily; this might have been a tendency much multiplied by their forced association with Norman overlords, but I think the language will come much closer to Middle English than one might guess even without that. They might lack a whole bunch of words common to OTL modern English but remarkably many of the more recently borrowed ones, the tendency to use Greek and Latin terms for prestige, along with whatever languages are fashionable in their day--Italian, and probably Parisian French, and Spanish, and eventually Native American and Asian words will be proliferating because that is the kind of things the old Anglo-Saxons were up to already in Alfred's day and generations before. The English will be looking for opportunity wherever they can find it and involving themselves, sometimes to their regret, in Continental affairs as they see fit, or perhaps as would-be foes impose on them from time to time. Thus overall their impact back on the Continent and world beyond will be broadly similar, and thus the overall development of Europe and the world will roll much as OTL, Conquest or not.
I personally would be sad to see some aspects of how England developed lost in a non-Conquest ATL, but by and large, especially with my assumption the broader strokes come out in the wash whether under Norman or Saxon management, I count Harold repelling William (and probably seeing him dead in a ditch at that, I hope) as a victory for basic decency anyway, and perhaps I have a softer spot in my heart for poor Harold than his real character might warrant--but I think of him as a good king bad things happened to, along with his people.
And with or without Norman ties, English people who are better off will still be wanting wines from places like Bordeaux, and exotic goods from the Mediterranean and beyond, and will be scheming to get them, by honest trade when they must, by the sorts of piracy that have comprised so much of English-speaking history when they think they can get away with it.
