That's an item, not team powerup.
I don't think that any of those powerups would be welcome in current game mode, unless developers used some wizardry to make them balanced. Also you stole ideas for Iron Curtain and Chrono-thing from Red Alert 2.
I would however like to see team-funding mechanic. Not necessarily used in current Command & Conquer game mode, but for other potential game modes. For example, I wish that one day we get game mode where team would need to pull resources together to build base and base defences. Also multiple harvesters and tiberium fields behaving like in RTS games (disappearing when harvested, spreading too far if not harvested).