I can see them allowing other players or at least your companion on the multi seat ones.
I don't think we will see this till 6-8 months down the line. There has to be good amount of testing. They could work in a mechanic similar with the flash point group conversation checks over the head. The owner would have to click to allow each to keep from people jumping in and players would need to be groups already.
It's very possible.
I'm sure over the next 12 months we will see a good deal added which were just not ready for the launch date but were already in the works.