This is in the roadmap of 4.0, isn't it?
It was, but externalizing kinda took up the whole schedule. Worse comes to worse, I'll just adjust the randomization so you get all UFO types and terror sites. It's still fully random, but most people can't tell the difference.
In any case there will be a feature coming so people can play around with all the Battlescape features without that pesky outdated Geoscape getting in the way...