I have to admit I was skeptical about the whole idea of the new add-on but after reading Lethal's notes its really sounds great in my opinion.
I still avidly play WoW and everything they are doing will improve the game where it currently falters.
I agree though, the game is not as big as it used to be but thats not because of how its developed (because it definitely has progressed and your a fool to think it hasnt) but its because people got bored of the concept (which can never change). I miss the 40 man raids and the rank for PVP (I was Lieutenant Commander which was a lot of work to get to) too and would love to see them come back but there just isnt the capacity for it anymore.
Its like any game. It will always dwindle, especially over 7 years but its still a great game and no MMO has rivalled it what so ever.
If I was being selfish, id tell Blizzard to put all their cash into getting a film out about WoW. It would inevitably be great and bring millions of players back or get them started.