What if Serbia became a super power?

Skanderbeg was not immortal; any benefit from him is only fleeting. This is a weak argument to make for nations over centuries.

Hungary may be momentarily internally distracted, but that doesn’t last forever. They are still right next door and larger. The Ottomans were also more than one trick ponies at this point.

I’d advise you to set a single PoD and date and then explore things from there, rather than trying to load up your bet. A single bet (X team to win) doesn’t pay as much as a multi with three legs (X team to win, Y player to be first scorer and Z player to be top scorer) but is simply more likely. It has to jump through less hoops to be successful.