First we need more races which is hard considering we can have a 128 races. I guess random could be done if you were allowed to set the the number of races you want on the map.

I have 53 now I don't think I'll hit 128 until we're able to share races...  But we'll see..

Perfect solution.

This really is a must at some point, picking your own enemies let's you start plotting your strategy earlier than necessary.

deleted double post

It was confirmed in a chat earlier this week that they have plans to add a "random" button for opponents. (which I took to mean, randomly generated to fill, say, a 100 player map).

Won't make it into the initial release, but it's coming sometime.

Hope this helps.

I think that will become more possible once steam workshop has been integrated and people are sharing custom races as if you choose a hundred player game it clearly can't make them all unique at the moment.