Everything else aside, Terran and D'Hara have pretty much zero reason to continue fighting if Barca defects. I mean, D'Hara is intact, Terran is intact, and most of the rhetoric was over reclaiming Barcan regions, yet Twainwood defected. OOC, I simply don't see this lasting much longer.
Rynn would rather be fighting Lurians anyway. That's the cool thing to do.