Again to go back to domination; one of the gameplay modes was to buy an army from a pool of credits, and then drop them at an area on the map with a dropship. What about allowing this gameplay mode? When sending a challenge to other players one would choose the amount of starting credits and the number of drop areas. This should be relatively easy to implement since it is already available in single player?

A totally different gameplay mode would be to disband all borders and instead place resource structures throughout the map. Income would then be given by the amount and size of resource structures controlled by end of round. Purchased units could be placed for example only next to spawn/factory points which would also need to be purchased and placed beforehand.

Both these gameplay modes would make it possible to have more than two players on a map, if that is at all possible with the game engine...

New and optional gameplay ideas sound good to me.
Even though 3 or more players doesn't interest me, apparently it does for others.
There have been several interesting ideas proposed.