I think it must be even less! say 20-30!! or even 15!!
the developers cannot nicely expand the range of their player capacity. Even they lose some good players.
what I mean is; the population of consistant players is not quite high.
let's say it is 200 or 300 good players always try to get into everyworld and compete.
if tribe capacity is 200! these good players has to merge at some point, and there will be 2 or 3 major tribes competing.
but if the capacity is low like 20-30, there will be always 10 good competitive tribes! isn't it nice to have this kind of competition?
I even more like to see 100+ good competitive tribes in a world... therefor, according to estimated consistant player number, we need to lower the tribe capacity even to 3 players XD