User blog comment:David Bear/Sonic's home world is in fact Mobius, not Earth/@comment-4920563-20130423185236/@comment-1669199-20130424221613

I think it'd be too much of a hassle to make such a cross-over game. And even if it wasn't, I can't see many exects from SEGA or Capcom taking any terrible interest in the idea, so it'd probably get vetoed out anyway.