What if the Habsburg faction in the continent-wide struggle for Spain's throne after Carlos II's death had somehow won in the end? What are the overall effects on Europe?
In my view, Britain was as wary of a surgent France (as per OTL) as of a resurgent Habsburg hegemony. Thus, i could theoretically see the british supporting the cession of some small territories to France after a defeat in the war, such as portions of the austrian netherlands.
What are the effects on the spanish colonial empire? Would a continuing spanish Habsburg dynasty have an effect over reforms in the americas?
And what about Austria in itself? One could presume that a victory in the war would lead to different marriages for Joseph I and Charles VI -- no Pragmatic Sanction?
Would Gibraltar still be ceded to Britain?
Actually, they wanted the Austrian branch to hold onto the Netherlands. Once the Spanish and Austrian branches reunited, the Stuart-British (as in Anne) in OTL thought "wait, we don't want a super strong catholic block in charge of Spain and Austria." In TTL (where the Hapsburgs win) the Stuart British would first think "Yay we win. (branches reunite). Oh... oops." However, the Hannovers will ascend to GB. The Hannovers only came to power thanks tot he Hapsburgs so they will think "Oh yeah, my backer is in charge of Europe and I only needed him in charge of Germany (geographical term, not the nation that doesn't exist yet), Hungary and Italy (again, geographical term)"

Look here where Kellan provided insight


I have created a sequence of events beyond your scope. I provided a sequence of events after Charles III of Spain becomes Charles VI Holy Roman Emperor and still lacks a son. if you have speculations on that particular situation, you can post yours there. If it's just about the Hapsburg-English coalition winning the war of Spanish Succession, safe to say the English would view that as a slip-up but not unsalvageable disaster and whent he Hannovers ascend it becomes all good.