I know the full game isnt out yet , BUT with every episode that is supposed to be released 1. Do you expect new units? 2. What do you want to see?
Without a doubt, Blizzard will continue to expand with the next games, the Zerg and the Protoss. Each game will most likely have a new unit for each race, possibly new game mechanics as well. We don't really know what to expect, but I am almost 100 % sure Blizzard will include new units in each "expansion". On top of that, there will be PLENTY of new units in the campaign, including bringing back some old units, in fact. All of them as Blizzard has said. Note: The game is still in beta ( technically), Blizzard can do whatever they want with the current units and such. If the balance is off. Expect a new unit, or a dropped unit, but we are far, far, far in to the beta stages and I highly doubt this.
Sniper64 made probably the best case so far. Because of each expansions focus on the other two races, aside from the obvious campaign tweaks for each race, i think it would make sense that since they have the spotlight on those races that they would also tweak the multiplayer for it as well.
they will tweak the multiplayer for every race, not just the ones with the title. Otherwise terrans would have less units. They are just expansions with a campaign focus.
They want to keep multiplayer fresh. The expansions will have new multiplayer units or I'm eating my horde insignia hat. The question is... when will the x-pacs come out? Damnit, I think I want more already... I'll never have enough SC.