1. TrueOf course, doing what you recommending involves certain dangers:
1. Prussia has an excellent army of at least 40,000 and only a part of it is engaged in the WoSS and even these troops can be recalled back home. So this is not going to be a simple walkout.
2. Attack on Prussia means a brand new war which can be joined by Denmark and Saxony.
3. The maritime powers want a balance on the Baltic and may support Denmark just not to let Sweden to disrupt it too much even by annexing the whole Royal Prussia. BTW, the Prussian Prussia is now independent from the PLC so the vassal schema is not going to work while a direct annexation of both Polish and Prussian parts is problematic both internationally a d just resources wise: as OTL example of Peter demonstrated, nobody wanted to have a single absolutely dominant power on the Baltic Sea.
4. Prussia wanted Stettin but did Sweden seriously wanted something from Prussia? Something worthy of a big war?
How about a somewhat different approach to the issue? The block Sweden-Russia is being too powerful for Prussia to try any adventures at Sweden expense
3. I am not sure about this point to be honest. Would the Maritime Powers try to escalate things when they have bigger fish to fry? If they were in peace with Louis, sure. Even if they were involved in a small-scale war with Louis. At these circumstances though, it would be very counter-productive for the Maritime Powers. William went into great pains to isolate diplomatically Louis. It would be something out of character to make an enemy out of a Great Power, especially one in a more secure strategic situation as at least one Minor Power is its ally. During his whole adult life, William was striving to contain Louis. He wouldn't push Sweden to french arms for Danzig.
But I didn't explain myself correctly. I am not arguing for an attack against Prussia. The opportunity I am talking about is Royal Prussia and Danzig. The war with Prussia will be inevitable at some point in the near future. But not to outright march to Konigsberg or Berlin.
That was indeed a disillusionment for swedish diplomacy.to make sure Russia is not treated like Sweden was at Fontainebleau 1679.
You are absolutely right and I concede the point!The line of thinking - that this nation might one day overshadow ours, and we need to strangle it in its cradle belongs to the era of nationalism and would not really exist until after the Napoleonic wars -with Bismarck and the unification of Germany as primary examples of this. It would not be in Karl's world view to go after Prussia before it becomes a threat - especially so since he was really, really big on the divine rights of monarchs and that wars needed to be just.
Post factum this time will be different than 1679. Sweden won't be exhausted, its fleet and army intact. An ally covering the flank. The PLC without a real ability to cause big trouble and neutralized by Russia. Judging from the 17th century what may the Swedes expect of the Maritime Powers? At worse, use proxies providing subsidies. A combination of Denmark and Prussia is not that threatening in the greater context. It seems to me that swedish confidence will be greater.Just as seizing Danzig it would also be against Sweden's medium term interests - as soon as the War of the Spanish Succession is over, people will start looking at Sweden again. And Karl knows this - he learned from his father how dangerous it could be to provoke all your neighbours at the same time.
In general, I have to admit that I am enamoured with the concept of dominium maris baltici. I root for whichever scandinavian power is close to achieve it. And I am getting carried away !