You can't mention low populations these days without people going, "NuH UH!!! My server always has 3000-4000 even at off hours!" Regardless of the numbers, it was obvious to me that there were far less people in the middle levels and the influx of players has greatly slowed.

That said, I don't really think FFXI is gonna bite the dust all that soon either. It's about 5th in the world last I checked and still has a decent lead on it's nearest followers.