Unless you drive them all away.
Can't you see the mud is slowly shrinking? You need new blood. You need to develop it, and you need to hang onto a portion of it. Plenty of people that go ooc to start with will learn not to. But if you make their lives hell they'll leave before that.
How many of today's vets do you think never went ooc. How many would still be here if some doofus decided to multi-kill them repeatedly and full-sac each time?
I know for a fact that a current shifter multi-killed a newbie warrior 4 times within about an hour recently, each time killing him as he regeared. Now I've killed that same warrior a couple of times, and both times he stayed impeccably ic, probably because I wasn't a cock about it.