An Online Game can survive if population is directed to the same places.
Like PSO PSU and MH3 there have always been only a few servers but because the way the games are set up there's never lack of people to play with and the small hubs seemed always lively.
I guess the big issue is that will SE try to combat sudden rush of new players (though it can't possibly be as large as in the release weeks!) by adding new servers or will they prolong the release long enough to deal with the current server issues?
