If you check out the progress page for CoE3
http://jaffa.illwinter.com/coe3/coe3progress.html
you will notice AI getting mentioned often. Johan tends not to be too specific what he did when he posts it (he likes to surprise us) but they do show up often. I think he enjoys it. I dont think we could keep Johan from tweaking the AI even long after the game is released.
There is also trigger commands that the players can use to write responses into a map. You can create your own events and surprises. Entering an area, or a site, could trigger a sudden increase of enemy units becoming available. Getting too many of a certain unit might trigger a revolt where many of them switch sides. I cant wait to see what the fertile minds here come up with.