I'm talking about things from 2.8.5 that were there right before it was shut down like certain training missions like the Eagle tower obstacle course, vehicle training, AT4 and the bunker busting version of it, Javelin training, ES2 objects even though they have no purpose. Also certain missions like ES2 Border, and the one SF map including the use of Hummvees I can't recall the name though. Also is it possible to make the ingame server browser working again? I honestly would love to see this game grow back to that point it was when we were left oh so suddenly by the creators.
The answer to pretty much everything is a no.
Co-op maps are not currently possible in AA 2.5 as it doesn't possess the same AI capabilities as 2.8.5.
Also, we cannot add new weapons as we do not have access to the source code. Anything that can be done has to be done through mods that run on top of the game.
I don't think it is possible to get the in-game server browser to work due to how the authorization is set-up. It has to be run through the Assist client. I could be wrong though. Wait for Eliz to comment on this one.
Not sure why it's a big deal to have to close the game out to join a new server.
Other training maps could be possible (as long as they don't require weapons or vehicles which are not in 2.5) but not likely.