I hope Bryant Gumbel wouldn't be a serious choice. I haven't liked him since he was in LA news many moons ago. He's always struck me as both smug and smarmy. I think the co-host needs to have more of a sense of humor and be warmer. BG's kind of cold and humorless, IMO.
I think the right co-host could really bolster the show's ratings, but I think they have to NOT try to duplicate what Kelly had with Regis.