Chester will probably sound great. For whatever reason he seems better at pulling off the harder stuff live than the easier stuff. (Ex: The chorus of New Divide vs the verses in Leave Out All The Rest).
As far as Mike goes, I dunno. Chester could actually sing the "god bless us everyone" part for Mike. I think Mike could pull off the "lift me up" part.
I don't think they'll even attempt to make the song sound as layered as it does on the studio version. I don't think there would be anyway to do it and have it sound good.