you are entitled to you opinion but i simply dont agree with it.
i havent played MoP and at this point i dont see myself picking it up anytime soon so i cant comment on how i would feel about the game but i can say without any bias that my favorite time period of the game was TBC. i started playing just a few short months after vanilla was released. i enjoyed vanilla wow very much, i played almost non stop from the time i start playing in vanilla until i stopped playing my way thru Cata. a few breaks for a month of two here an there.
despite me being more excited about Cata (shocking i know right) and thinking that WOTLK had better story and epic feeling, i still didnt have as much fun or enjoyment as i did during the entire run of TBC. note that im not saying that WoW would or wouldnt be better off today if it had stuck with TBC business model. im stating that i never had a better time in game as i did during that time period.
to answer the op, quite simply no. the game you seemed to enjoy (the vanilla/TBC) model will never return unless they add some sort of legacy server thing, which is highly unlikely. i also dont believe WoW will ever see 12 million subs again, possibly but again i doubt it