Suma wrote:
"It would be almost as developing brand new product."
I really think that hits the nail on the head. Forget about improving ofp multiplayer. Improve the single player game by all means, but if you cannot improve the multiplayer to the level needed then why throw good money after bad. Start work on ofp2 instead.
Note I am not just referring to the lack of join in progress, that is merely one of the end effects of the real problem : The lack of a true client/server model. This also causes problems with trying to run complicated scripts in multiplayer games. All the scripts are running individually on each machine with no attempted synchronisation.
Seriously, if the client/server model can't be fixed through patches then don't waste your time.