I don't think they'll switch parties on their own free will; I think the party establishment will kick them out
In Maine? Hardly. Those two are as conservative as you're ever going to get in New England. Centrist and left leaning Republicans are a much larger part of the Republican base in New England because the Democrats in those states are a stone's throw from being complete Commies.
The Dems aren't a stones throw from commies, and the moderates and liberal leaning Republicans aren't a larger part of the GOP base in New England because of that. They are a bigger part of the GOP because they are the only ones that can get elected in New England. Even with that the GOP in getting pummeled on the state level as well in New England as they are losing sttae house and senate seats in droves.