Since I created this this thread, two huge occurrences have happened:
•Sacramento will host the Athletics for roughly 3 years before the move to Vegas;
•and Salt Lake just landed the NHL Coyotes...
This effectively eliminates Salt Lake from contention as an MLB candidate, as they now have three major league franchises. They'd be far and away the smallest city with four franchises if they land MLB, as the smallest city and market with 4 franchises currently is Seattle. MLB is in the revenue and eyeballs business, they aren't about to take the risk of being the 4th franchise in a market that hasn't yet shown a history to effectively support 3 leagues...
And this effectively shoots Sacramento to the top of the expansion list. The A's will be playing at a field owned by the Kings' owners, so MLB already knows there's a built-in ownership group that can afford a franchise, if awarded one. Also, with this Vegas move on perpetually shaky ground, Sac can really show out these next several years. Either the A's still go to Vegas and we end up with an expansion team, or the Vegas move completely disintegrates and we inherit the A's...
Sacramento is in a really, really good position, probably should be seen as a favorite right now...