Upvote:1
Catholicism, whose liturgical language is Latin, is prevalent in Bavaria, so as long as there have been priests and parishioners there, Bavaria has had a population of Latin speakers, for example in the Seminarium Internationale Sancti Petri.
Upvote:9
There were two Roman provinces that encompassed part of modern Bavaria: Raetia and Noricum.
In both the ancient population primarily were herders and loggers, not farmers. So they weren't particularly populous provinces. Both were essentially overrun by Germanics during the Migration period. These "Germanics" were primarily speaking either West Germanic Upper High German (eg: Alemanni, Suebi, and Lombards), or East Germanic languages (Goths, Gepids, Vandals, etc.)
The East Germanics, as pastorlists, tended to be accomplished hors*m*n, but also light on the ground. That meant they made a much bigger impression in histories of the time. However, it was the more farming-oriented High German speakers who settled down and culturally took over the area. The Bavarian spoken in the region today is a descendant of High German.
As for what happened to the Romans, again they didn't have a huge population in the area. In Noricum they had 8 known colonies, all in modern-day Austria or Slovenia. It appears that the largest was the Roman capitol Virunum (in modern South-Central Austria), which lasted until about 610.
In the territory that was Raetia, there is in fact one population still speaking a Romance language left over from Roman times: the Romansh of SW Switzerland.