Whizbang Dustyboots
Gnometown Hero
I think the closest they'd come to 5E Birthright would be a setting-agnostic book expanding Bastions into full-fledged domain rules, with Cerilia as an example setting inside the book. I just don't see them ever saying "hey, you know our fourth-tier kitchen sink setting? We need to get that back into print."I don't see Birthright or Mystara in that list, and I'd personally think those settings would be less likely to get mentioned than Dark Sun.
(Mystara would be the third-string, for those counting.)