Excellent post! Very thought provoking.
I play capital kill games on large (125x125) maps with 3 AI enemies and usually there is no interaction between players until I locate and destroy one of them. My capital has never been located so I never even bother defending it these days. Because of speed I found little use for air transports. This has given me ideas for customising units to encourage a faster more exploratory game.
The interesting thing of course is that I can modify my gameplay to match the new units, but can the AI also adapt? I suspect not.