Maybe that's why I had to quit playing on Elendilmir...same number of annoying people, but at least BW has a break from the inane glff posts during the wee hours of the morning.

That said, I think the answer to the OP is the same as after every other MMO release in the last 4+ years: Some oldbies left for a change of pace, some Jedis left for the lore, and some newbies who weren't yet invested in LOTRO went to try it out. Some of these people will be back, some play both, some you'll never see again. Not enough to make a huge blip anywhere but in PvP and some of the older and raiding kins. At the same time, new subs are going up, so it seems like the population is staying steady.