WNBA investigating and will smack down the Aces for the second time over something like this. Competitive balance goes in the garbage if every free agent know they will make x+100k in Las Vegas and just x anywhere else. This will lead to super teams.
Considering that this is essentially an endorsement deal with the city that the organization had nothing to do with, I highly doubt that.
As for "competitive balance", there's nothing stopping the other major WNBA cities (LA, Seattle, NYC, DC, Dallas/Arlington, Indianapolis, Chicago, Phoenix, etc.) from striking similar deals.
It's put up or shut up time. Enough with the investigations (i.e. whining). Either you care about these players or you don't. The city of Las Vegas just upped the ante. Your move, Seattle and New York (and LA, Phoenix, Minneapolis, etc.).