I don't really think letting us use divine intervention or the True Res scroll to wave the problem away is a good solution or something I actually want to see, I'm more just using them as examples of how having tools that seem like they should be able to address the problem, then not being allowed to actually use them, is incredibly frustrating. (the true res scroll is also a reminder that if you give D&D players magic that powerful, they *will* find uses for it you never considered, but that's a different topic) Obviously any actually satisfactory ending would involve serious effort to reach whatever conclusion you get to, same as the other origin character quests. Hell (heh), I don't think the 'back to Avernus' end is necessarily impossible to make work better than it does now, it's just in its current form with no follow-up it still feels incredibly bleak.
