Indeed, at middle-long term ruling from Constantinople their ruling dynasty and presumably at least part of their political and militar elites, would surely, over time, to intermarry/fused with the Greek/Byzantine one, and so would at certain degree, at least, they'd be Hellenized. But, also, I'd suppose that given that,IIRC, that the Hellenization process could be somewhat equilibrated and/or confined to the new royal/imperial capital's elites. Cause, while it would still be a Balkanic State, that in the new empire so formed, population wise both their Bulgarian and Greek populations would be relatively equilibrated...
