Yeah, that's more-or-less what I read. Hopefully by then I'll have another natural 5*, but considering this account already has more solid characters than my launch one (I spent every crystal I grinded, and only managed one 5* character and even she came at 5*), I think it was worth re-rolling. I wasn't in very far anyway, since I stopped playing for a while and just did daily logins.You'll be set to clear the game at least. Post game grinding you're gonna want to hope for an AOE sweeper though, but Mariel will be able to heal you through anything you can throw at her. Mine is only 4* and she's a mainstay in any party of mine.
I will miss the healing robot-bot, though.