There is an article, written in German, where DICE acknowledges the things that they did not have time to implement in BF42 because EA would not give them the time neccessary to complete them.

Here are just a few (translated by google)
– destroyable buildings and Spawn points
– parachute price increase (Not sure what that means?)
– dynamic Multiplayer campaign with effects on the following maps (That would have been very cool.)
– shooting as a passenger in vehicles
– a good communication system, approximately by Headset or speech recognition for Bots
– vehicle formations

It looks like a lot of the things made it into Battlefield Vietnam. Is it too little, too late?

Additionally, a lot of vehicles were removed because EA felt they caused too much CPU usage on the server, preventing servers from running 64 players.

The article is interesting, if slightly difficult to read. Check out the english translation.