Wow. If his cunning opportunism pays off, it’ll exceed OTL count Rudolf‘s rapid ascent - given his uncle is Pope I’m guessing there will be no issues with a formal HRE crowning?
My instincts are telling me Leopold's gambit won't pay off or his family won't keep the crown for very long, but I'm a huge sucker for convoluted come-from-behind instances of OTL things stumbling into alternate history. In spite of incredible hurdles, the House of Habsburg stands poised to claim the title of emperor.
It’s fun to imagine the reactions of everybody in IOTL there had been a Habsburg Pope and Habsburg Emperor simultaneously…
I do enjoy the ATL possibilities of ‘completely different route but ending up in the same place as OTL’. It’s fun to play with. I don’t mind the parallelism, provided it’s done creatively and entertainingly. Not that I want to have everything play out that way, but the occasional bit here and there.
Vlachia and ‘friends’: All this stuff is setup for things 20-30ish years down the road. But a war over border provinces of a buffer state (from Constantinople’s POV) is very different from a massive invasion of the imperial heartland. Stakes are much lower, and the war would be fought much further away from Rhomania’s center-of-gravity.