Questo avrebbe salvato l’impero?

Nein.

Which empire?

Dude this is going to trigger so many neomarxists here

The issue was not that there were too little crowns, it was that there were too many. Austria should have stayed as the austrian empire. Under the empire they were a way bigger player because they didnt have to take the hungarian crown into consideration. Hungary kept the empire back in aspects where it should have advanced, hungary by WW1 was still largely rural while austria industrialized. A illyrian crown would just make more issues as they have to take them into consideration aswell and there would not be an army under one language because neither hungary nor illyria would want to use german for their troops