Re: I am for DLCs - and tell you why!

Absolutely, paid DLC in the model of 2 or 3 expansion packs would work great here. I'd go further and suggest the best way to format these would be each being it's own campaign which adds maybe a new ship or two on each side, new maps, new capital ships and a much of singleplayer missions, these don't need the level of cutscene polish the main campaign had which should keep costs down. Alongside that a free update would be made that added just the ships and maps for multiplayer use. That way you recoup the development cost from people buying the DLCs for the mission content but you don't split the multiplayer player base.

Adding and expanding on game modes, making single player available in coop and generally improving and adding to the mechanics could all go along with these free updates with paid DLC campaigns funding them. Best of both worlds. Frankly if Motive don't want to do this I dare say a small indie dev could be found who would jump at the chance,