I don't think Virginia would be able to support moving the Amtrak electrification changeover South from DC without dual mode equipment.
Take a hypothetical Fredericksburg line electrification project, ignoring the freight track clearance issue. If Amtrak doesn't have a yard with some electrics, a couple of platforms for a 20+ minute dwell time, etc. Then they're not going to use the Fredericksburg electrification - only VRE and maybe MARTA through service to Alexandria would. Even if Amtrak extended the wires south to Richmond so they could use them, it's still tricky - Richmond isn't really a terminus right now and Virginia wants service to continue south, east, and west.
The only way I see Amtrak using overhead power on the VRE network is if they don't need to change the locomotive out.
The only way I see Virginia putting up overhead wires is if the frequency south of DC in peak periods is if they're setting up a baby Northeast Corridor - at least half hourly peak period service on both Amtrak and VRE, with hourly off peak, figure mid 40s daily trains each way. If only 20-odd daily trains could reasonably run electric, that could be a dealbreaker. This suddenly applies to any branch coming off of the NEC - put up wires where your higher frequency commuter line wants to be, and get bonus Amtrak use. Heck, the potential South Shore Line passenger bypass could use Airo. (Admittedly not the exact same APV as the East Coast, but Airo is Vectron derived and Siemens includes 3kv DC as an option for their multi mode Vectron locomotives.)
I don't see additional major Amtrak electrification projects in the near term. The best candidate routes (DC to Alexandria, Fredericksburg, Richmond, Raleigh in stages, and NYC-Albany) are going to have to be state led projects unless something changes. But not requiring equipment changes for Amtrak is a pretty big deal, I think.