The Aviators relocate to a new market
Do not be surprised if all the talk of the Aviators staying in Vegas is all bluster to keep attendance up. It would be reasonable to assume that if attendance does decrease once the A’s move, the Aviators will relocate somewhere else to increase attendance and profits. The most likely candidate for the relocation location would be Tucson, Arizona.
MiLB experts may point out that Tucson has had PCL teams in both of the last two decades that ultimately relocated and this is true, but the reasons they relocated were more complicated than simply lacking attendance. It is true that in 2007 and 2008 that the Sidewinders had among the lowest attendance in Triple-A, but they had been sold and all signs pointed to them moving to Reno. Just like the A’s in Oakland now, why support a team that is about to dump you?
The second iteration of Tucson in the PCL was never going to work, they had a boring identity (the Tucson Padres-guess who their affiliate was) and the team was very clear that they were only there temporarily until they could get something figured out in the San Diego area. Their plan didn’t work, so they stayed an extra season in Tucson with little support as they continued to look for alternatives. This team still exists today as the El Paso Chihuahuas.
While a new field may be necessary, Tucson is the second-largest market in the entire United States without any form of affiliated baseball. A Triple-A team would be justified.
As far as affiliates go, I think there is an easy answer here: The Reno Aces become the Las Vegas A’s affiliate and the Tucson Sidewinders/Toros/Aviators become the Arizona Diamondbacks’ affiliate. This relocation option is easily the easiest and does the least amount of changes to MiLB at large. It provides markets with affiliates that make sense and are about as close as you can reasonably get to the parent markets without sharing the metro.