I mean expanding on character endings seems more likely to me than anything else I've seen in a theory. Between raphael, zariel, hope, not to mention all the teasing they did in the epilogue around avernus. But raphael probably isn't even dead given his father is mephistopheles arch devil of thr 8th ring its likely raph is regenerating there. I think there's more to avernus than just the forge and the dlc would likely have the forge as a side thing and not its main purpose.
