Is he right? Fortunately, there's a site that tracks numbers (as reliably as you'll find for public information, anyway -- certainly Blizzard has access to much more information) on exactly that. WarcraftRealms' list of classes over time does prop the "declining Hunter" theory up -- as you can see (from both Alliance and Horde totals), Death Knights took a nice bite out of all the classes for a little while, and Hunters have been on a pretty steady slope down since mid-January, when patch 3.0.8 hit the realms. That, of course, was the harsh Beastmaster nerf, and ever since then, Hunters have had some real trouble recovering (not to mention that all class playtime is declining in general -- despite their slope downwards, Hunters are still in the top three classes played anyway).
Is this the end of Hunters? Not at all -- Blizzard has already said that they are cyclical about balancing classes, and a heavy set of nerfs on one side of the cycle is usually accompanied by a burst of buffs on the other. Not to mention that the most interesting Hunter changes, the ammo revamp, hasn't yet found its way to the game. Reworking of ammo (in addition to some likely buffs there), will probably bring lots of Hunters back to the stables, so to speak. But it's true, Hunters are on a downward turn lately.
[via WoW LJ]