Naval vessels would have very little impact on regular ground forces. I would definitely not implement playable infantry.
It could be very fun actually. World of tanks is introducing a longer gamemode as well pretty soon. Wouldn't hurt to turn Gaijin's head in Wargaming's direction from time to time.
Obviously it would be RB without markers in the ideal. You remove AB and random battles as a whole, keep sim events as they are.
If you can come up with a gamemode that is fun for longer periods of time, and that supports in the realm of 64 players, with a balanced SP system, then I'd be all for that.
If you were to base it off of the April fool's event's spawnsystem, and made it so you can go in with tanks and aircraft as well, however you choose what type of vehicles you want to be using primarily. So if you want to be a tanker primarily, aircraft are spawned in with SP, and if you go in as a pilot, tanks are spawned in with SP.
Who knows, maybe this could work. I think if you limit the amount of primary pilots, then sure why not. What do you guys think?