At this point, I'm not so sure it's really an issue of motivation for the developers. There are just certain things that need to be in place first before online mode can be done without having to redo the whole thing a year later. So far, these things have been AI, skidding, and physics.
On the other hand, I don't think it would be a bad idea to hire somebody who's been involved coding online multiplayer for some big-name commercial game. Actually that depends... not all commercial games have an equally good online mode implementation. So hire somebody who wrote a good implementation then
