Las Vegas on Deck for #31.
The issue with Charlotte is lack of a soccer specific stadium plan, much like Detroit's bid. This author brings up the precedent of the Seattle and Atlanta exceptions, but at least in the case of Atlanta, the stadium wasn't existing and was actually designed with soccer specific and soccer friendly criteria (I read they visited European soccer stadiums for design ideas). Seattle was added earlier, when expansion criteria maybe didn't quite have the SSS emphasis it has now. Plus Seattle was a proven soccer-crazy area. Tepper has heft, but so does the Detroit ownership group. Unless these future Charlotte NFL stadium renovations significantly add soccer specific elements, I don't see what would separate Charlotte from Detroit.
He predicts Vegas' selection in part on the assumption the ownership group would at least include Bill Foley, the owner of the Vegas Golden Knights NHL franchise. While Foley has expressed his desire to submit an MLS expansion bid, the primary prospective ownership group to emerge in Vegas was the very wealthy Renaissance Group. It was the Renaissance Group who won the right to exclusive negotiations with the Las Vegas city government to build a new SSS on the current Cashman field site. Foley has said he wants to use the NFL stadium being built for the Raiders, so see above for my opinion of that. But I hope Vegas does get in 'cuz I live in Vegas.
And I'm so glad mid-market, non-glitzy, non-sexy Salt Lake City got in when they did.