[offsides]

1) Additional SP campaigns are definitely necessary. The existing one can be given more longevity by adding in some random placement of the defenders and/or AI difficulty levels, but it only helps so much.

2) If nothing else, you need to add the extra conventional units (GEV-PCs, LGEVs, hovertrucks and trucks) to the game. That opens up a lot of things, especially scenarios like Operation Newspaper which would be perfect for implementing as a single-player scenario that's easily randomized for at least some replayability.

Note: I haven't had a chance to play since the GEV maps and scenarios came out, so I don't know what has and hasn't been implemented with them. But obviously more of that would be good too :)