I actually checked some tours that were hitting NYC and the surroundings and it didn't enlighten me at all. Usher? That would be WTF? for sure, but I wouldn't want to go to that show at all. I wouldn't pay for it anyway.
I still think if Kris should open for someone for some dates, I think it should be with someone similar. The opening acts that I've liked the most were acts that were similar to the main act I was going to see (like The Stills when I saw Metric, Lisa Hannigan when I saw Jason Mraz, Gary Go when I saw Mika, Ryan Star when I saw David Cook, etc). I saw a weird DJ and a hip hop singer when I saw Coldplay live and I hated both, it just didn't have the good vibe.