Unless TWI goes in a new or depending how you look at it, old direction, and makes true CA a priority, I doubt you'll see much in the way of vehicles in a future RO. The current community doesn't really care about armor, the hardcore tankers are long gone. With mobile spawn points, (SoSL), you don't really need transports, so players don't value them as such and use them mainly as suicide cap rammers and MG platforms.
If they choose to keep the gameplay similar to what has proven successful, I don't see why they would spend a pile of money on a fleet of vehicles. I'd bet on a couple per side, like now, without interiors.