Hapsburg
Banned
One could say that such a system of government is a republic. A Noble's Republic.Even if Byzantine Empire stands until 17th-19th centuries it wouldnt have been what it was in the past... It might have been evolved to a loose confederation of states (Kings, Dukes, Archbishops etc.) under an Emperor-elect... Just like the HRE at the time of its dissolution... BUT IN NO WAY A REPUBLIC!!