I always expected Total Annihilation 2 would go for the whole globe thing... probably well beyond the power of PC's at the time. Probably beyond the power of PC's now, hence the cartoon graphics. Removing map borders as a strategic consideration is cool though, chokepoints will have to be made with defences.
The interplanetary stuff is just gravy. I imagine it will work like the Superweapons and Bertha batteries in TA, where your opponent builds them to funnel your efforts towards them and away from his secret power stationss.