It seems as though it won't work. If tactical combat would be in, there would be no need for a separate viewer - as you could just as easily watch combat play itself out in a tactical combat mode. I hope I'm horribly wrong though, I'd love to see some interactivity.
I don't think he meant actual tactical combat with player intervention. But there have been mentions by Frogboy and the Stardock people that GC3 would have a more complex combat system, possibly with some pre-combat decisions. So the question is legitimate : what will be there? How will it work? Because so far, we have a few minor changes from GC2 with the introduction of new stats, but they don't yet really change combat all that much.