They're looking at a realtime strategy game...
It'd probably have to be more squad-based, honestly. Freedom Force (already ou tthere,) Myth, etc. World in Conflict, perhaps, since yoU *can* reinforce there, and it doens't need resources.
Play with a team of Masterminds?
Yeah - that's what I was thinking, PVP with masterminds is pretty much exactly RTS... isn't it? 
Oh yeah, and gladiator matches. Which are hella fun.
Please read my FEAR/Portal/HalfLife Fan Fiction!
Repurposed
Armies of hundreds of superheroes (and the opposing villians) just seems really odd.
If everyone is super...nobody is.
At some point, the majority of them just become minions, like G.I. Joe vs. COBRA.
Do what I do on my MM...
1) Find an outdoor area to fight, or someplace with a high ceiling.
2) Angle camera to directly above and zoom way the heck out.
Bam! Instant RTS Mode! 
Come to think of it, I think my love of RTS games is 90% responsible for my love of MMs.
The off-beat space pirate...Capt. Stormrider (50+3 Elec/Storm Science Corruptor)
The mysterious Djinn...Emerald Dervish (50+1 DB/DA Magic Stalker)
The psychotic inventor...Dollmaster (50 Bot/FF Tech Mastermind)
Virtue Forever.
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It would be the most off the wall fun RTS I'd ever play I can tell you that, easily multi-player, fully customizable armies of hundreds of heroes or villains!
Thought im sure programming such a game would be hard, id play it
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Come to think of it...
You could angle the camera and zoom way out during a Hami raid (or a Rikti (or Zombie) invasion).
Just pretend that you are in charge of ALL the heroes and that some other guy is in charge of Hami and his bud spawn. And of course, that the only reason that your troops aren't responding correctly is due to bugged AI. 
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Armies of hundreds of superheroes (and the opposing villians) just seems really odd.
If everyone is super...nobody is.
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Which is why I mentioned squad-sized, like Freedom Force or Myth. No reinforcements, no building - or World in Conflict, which is somewhat limiting in reinforcements.
Doing a Freedom Force sequel/mod kit for CoX would be pretty sweet.
Or a squad-based game with building that simulated base raids if base raids worked.
I guess I havent had the opportunities to explore those portions of the game it was a thought
It would be the most off the wall fun RTS I'd ever play I can tell you that, easily multi-player, fully customizable armies of hundreds of heroes or villains!
Thought im sure programming such a game would be hard, id play it