I have two concerns when it comes to PvP campaigns, and I'm curious as to whether or not I'm just missing something.

The minor one is, since there are many battles happening for the Imperial City, how many people in the megaserver areas might be "Emperor" all at once? Might be immersion breaking for Emperor from Campaign A and Emperor from Campaign B to be standing right next to each other.

The major one is, it seems that the area which is most likely to be harmed by population imbalance (and potential population drop) is that one area where people are locked into what are essentially servers. By this I mean that since people are locked into campaigns you'll see the same problem that GW2 is having with WvWvW. Populations may drop.

The megaserver technology allows for a lot of flexibility, but the area which could most use flexibility will lack it.

The best solution, I think, would be to make campaigns winnable. Maybe designed to last a month or two.