So how exactly could it work? I don't think I've ever seen anyone spit out an ENY formula- there's almost always a "I'm not sure how exactly it would work, but HT could figure it out" clause, and other people saying their idea will work, but not how.
How would it deal with missions? What if 2 bases are 5 sectors apart- one under attack by one country, the other by another country? Would people be able to defend both bases, assuming they had fewer total players, but everyone was in those few sectors? What would happen if they all sat in the tower for 10 minutes? A localized system would have to require a huge amount of work, it seems. It would have to compare so many factors in order to be an improvement, that I really doubt that it could work as well, or better than what we have.
There's one simpler alternative that encourages people to quit flying with the horde- Actually disable flight at 30, and ramp ENY up quickly initially. You guys would come up with all sorts of ENY alternatives then, but they'd still be for the same reasons.