Sub-Commander

A cool idea, but I think it'd be a nightmare designing that intricate AI system. Plus I'd rather the game be more micro intensive and rely on pure player skill than having AI assistance.

Don't be silly. It would use an AI identical to the AI we're using for any other skirmish. Every asset, even the AI needed to make it happen is already in game today. The only barrier to immediate implementation is the question of instantiating a new AI faction mid game. Some games require the factions be established prior to the start of the game, but I suspect if the devs are interested they have the means to enable adding AI factions at Run Time, if it's not already possible.

Hmm reminds me like in the old game called Conflict Zone. You could assign troops to a commander and give that commander special orders (attack, defend, build, support, patrol, etc) and he used all the units he got as good as possible.

At the current state of the game now with the AI I'd bet there's more than just that barrier you mentioned that isn't currently allowing this mechanic to work.
They're not even done with the naval part of the AI, let alone AI's cooperating.

It doesn't take a special AI to cooperate. Worst case, an allied faction would just ignore you and keep fighting enemy factions. Also, I'm not advocating any AI other than the one that was going to be developed regardless. This wouldn't involve special AI at all.

I'm not a power gamer or a diehard multi-player. I agree with your opinion to some point. I am focusing on adding a new layer of strategy to the game. I guarantee that only 1% of the players of this game can micro manage well enough to be able to properly execute a complex attack strategy. Most the time it is a mass of units sent at a persevered weak spot. I personally would rather spend more time mastering my enemy than just overcoming him massive numbers.

The sub-commander could be completely limited and operate off his own resource pool. The AI could be very basic and not capable of winning the game for you.

None the less. Your train of thought is compelling and if this game ends up having a competitions with million dollar prizes.. I would agree having assist AI would draw from the overall skill required by the game in its current state.