Is there a way for the Romance-Speaking population of Illyria to absorb and assimilate the Slavs that migrated into the area rather than the other way around? In OTL, the Istro-Romanians and Dalmatians survived for a little bit but eventually succumbed to Slavification. What would it take for the Romance -speakers of Illyria to absorb the Slavs in a way similar to the Romance-speakers of Iberia, Gallia and Italia absorbing their Germanic invaders?