VCU already shares that stadium. One issue is that the new MLB-set facility standards for AA are higher than what was required before. The gap to a AAA level is even bigger. Nonetheless, it would behoove them to build the new one to that standard. Several of the most likely expansion cities are current AAA ones, meaning there could be as many as 4 open slots in AAA. That's probably not until 2030 or so, but it's within the lifespan of the next stadium.
Sounds like the will lose even their double A status in the next few years without a new stadium.