I would like to see an option where someone can host a game with an AI as the host's player, so they could make a pre configured game available to those who want to play. If such a thing is implemented, there should be an option for the host player to "jump in" to his AI faction and take control at any time. It should also be possible for the host to turn control of his faction over to the AI should he need to step away from the computer for a bit. That way, the players already in game need no interrupt their session, and the host can rejoin the game by taking control of his faction whenever he or she likes.

Like a dedicated server? Would the AIs continue without the players?

Nah, just an option for the host of a game to turn the ai for his own faction on and off so he can do other things if he has to and come back to the game later.

If the host leaves, the game will migrate to another player. I'm pretty sure the game holds the spot for the dropped player for a while (it does for guest players) so you can rejoin, but you will no longer be host...