That remains to be seen. The discussion over the space combat portion of the game and the pushing of said "3D space combat" on the beta forums was one of if not the hottest topics. There seems to be a huge interest in 3D space combat DONE RIGHT. Also, there is only a small number of players CURRENTLY interested in the space combat in game at present.
There are some players who want it. But I also know many, many players who are not interested in space combat at all and just played the first missions. And "to do it right" needs lot of capacities. I'm quite sure multiplayer battles were planned in the beginning, but didn't work well. (Space station attack for example, where you start with 3 player ships on your side.)
@Utio: You have to pay the "space team" too.