The total serv pops is maybe more than 10k players, when we say 6k+ players we talk about connected at the same time.
If we reach 7k players ( or if we're still at ~6k an other month ) connected at the same time, I would really like Nostalrius team to think about a PvE realm option. The game has not be designed to support more than 3-4k players ( connected ) on a same server for vanilla and having 2 servers with both ~2-3k players would be much enough to reproduce Blizzlike experience

Time will tell us if this a necessity or not, if one month later the pop decreases to 3-4k or less then a second server option won't be useful and the overwhelming gank issues will fade away.