I think you may be referring to GPG's new venture, Demigods? You play two different kind of Demigods, one which sort of goes around kicking ass, and the other that generally focuses on commanding the underlings. But, individuals aren't controlling the ground troops. So maybe you're thinking of something else, but Demigods is the only thing I know of that I've seen reminiscent of the Colossi designs.
On the topic: The term I made up in my head for this is asymmetrical cooperative play. I think Battlefield's failing was in not providing enough incentive for the ground troops to obey the commander, and in using the grunt ranks to populate the commander's seat. Team motivation is all well and good, but if the commander had some sort of lasting power over the individuals, like setting point values for achieving goals they set on the map (Take this position! Worth 500XP), you might actually get people playing together. And, as someone else mentioned, it is hard enough making one game, let alone making two entirely different games, that then interface seamlessly for the end user. On top of that, to get to a point where you have enough people to be meaningful for an RTS commander, you're talking about an RTS/MMOFPS arrangement. MMOFPS is hard enough.
What about the MMORPG space? I know you can rise up to be the castle lord in Lineage, but it might be interesting to take that to the next level, and give those individuals city-planning capabilities, etc. In EVE, I think you can build Space Stations, which is getting into this area as well.
In general, the more aspects of a game that we can make human-controlled, and enjoyable, despite being different roles, I think the more fun that game can be (AI is great, and all, but good people are always better).
