I am maintaining a "guild listing" on our server.
By the amount of traffic on that post, and the amount of guilds on our server it is hard for me to see that the population is dropping much.
Have a look at the amount of guilds here, and keep in mind that there are probably several guilds that havent bothered putting a note in the thread (most likely there are more guilds not interesten in such a thread).
This is just our server though, but I can imagine that there are several other servers doing just as well, if not better. Of course there will be servers "struggling" populationwise, and I am sure there will be mergers eventually, but for now it isnt looking all that bad.