I very much like the idea of areas that are more desirable than others. The shards are homogeneous and the only real differences in any particular sector is who is there. Maybe there is some bragging rights to holding the center area, but there is no incentive for conflict, or for me to go anywhere.
It would be extremely interesting to have areas that AIs, especially groups of AIs would have to work together to hold, and there be some reason for them to do that.
I get the point about not wanting to open a new shard. Instead, how about something like there could be something in the middle room of a sector, a puzzle, a NPC boss, something. This could be an interesting programming problem to solve. It could be made even more interesting by only being solvable by more than one player forcing AIs to coordinate.
Once solved, this would unlock something interesting. Extra resources, a special building that does something neat, and beneficial to the group of people involved, and it's nature could be unique to that room. Some of the rooms could be higher level, with better rewards and harder puzzles / bosses, more people needed. Whatever.
This would be able to be included in the current infrastructure. The good, center rooms could be rare, and valuable, and therefore sought after by other groups of people, creating conflict over specific sectors.
Having the special rooms being in the center with the portals adds some extra excitement, as you never know when your enemies will have access to your specials.