As someone who lives in north america, i personally find that there are a HUGE amount of servers going at certain times of day (i'm talking tens of servers, relatively well populated). Particularly around midday to afternoon on Fridays and weekends there are a good amount of servers. however any other time it seems pretty much deserted, i find there are alot of EU servers until about 4 pm here, then things start to slow down.

I think there are still a good couple of years left in HD Fury's servers, personally. Unless of course something drastic draws the audience away.