i think this idea would need a tweak of sorts. As stated by yahiakh, leaders would have a nightmare of a time dealing with this. Good luck finding someone willing to try doing this. If there was a way to eliminate leaders from existing, that might help (as it would just kinda be a free for all, everyone do what they want kinda deal). The biggest issue I see here though is the chance for a landslide. You have nothing to prevent such from happening. The current set up, I could easily see all the pro's just deciding together to plant on 1 side of the map and then absolutely murder the other side. Era would be extremely short unless the experienced players actually decided to keep things even.
As for the capitals and super outposts, sorry, I don't think those will happen. Would simply be too much coding to add onto the game... and then we'd have an entirely different game with totally difference mechanics (not to mention, who would own these units/be able to move them?).
The possibility of a 1v1 with 2 huge teams facing off is possible, but there would need to be more checks and balances put into place.