Well, would Romanian necessarily be a monolithic bloc, here? I know very little on the formation of modern Romania, but the general singular language (split between three regions) could possibly be attributed to the isolation of the Romanians from the remainder of the Romance language groups.
In contrast, this Romania (which I will simply refer to as Illyria, for clarity's sake), would be part of the Romance continuum from Portugal all the way to Macedonia. The Dalmation city states could potentially be stronger, with easier ties to the hinterland, but could be subsumed by the Italians like OTL as well. Still, Dalmatian as a subgroup would survive. However, an Istrian group might appear as well, serving as a bridge between Italian (mostly Venetian) and purer Illyrian, which remains located mainly within the hinterland east of the Dinaric Alps.
if we're counting Macedonia as well, one thing for it might be it becoming the last remnant of any Latin Kingdom/Crusader state (assuming Islam even arises with a Migration era PoD is sketchy enough, but for ease of argument...). It would certainly become a region that would have a heavy greek influence, if it simply does not become Greek in its entirety.
Would Albania be subsumed, in part, to the Illyric picture, or would they simply take a good deal of loan words and from Illyrian/Italian languages, but not quite converting entirely to this new Illyrian.
Edit: I can imagine the italians trying to include the Yugo-Romanian region in their claims of unification, but it would probably fail miserably.
I'm not so sure they would be so unsuccessful; as it was, they had relatively large claims from the not-insignificant number of Italian speakrs OTL - even if the last Dalmatian speaker died out in the 1860s (I think), there was still an Italian (Venetian esp) strain present. And, as the entire Adriatic remains Romance, the illyrian spectrum will remain very close to Italian - though, Italian itself could very well be different (Venetian or Istrian may be the better suited for a middle-ground language for both peninsular Italians and Illyrians.
So, Istria (including a good chunk of what is Slovenia) and Greater Dalmatia could easily become part of Italy in this scenario - especially as Italy is a flexible concept to begin with, assuming all things equal. Everything west of the Danube, down through Bosnia and Montenegro would not be hard to be integrated. It's once you get into the South Illyrian/Serbian highlands, and especially into Macedonia, that you might find difficulty due to sheer distance. Though, if This alternate Italy also integrates Albania, then there's a reasonable chance they could bring Macedonia in (Janina too, but that's a different discussion).
You, of course, could have Illyrian develop into a political entity, or have it be dominated by Hungary similar to the Balkans in OTL as well. You've got over 1.5 millenia to play with, so virtually any of the above could happen.