I dont want to go into whole "game is losing subs omg dead", but the fact that it is losing subs is not secret. The dead part..well its far from it still.
Each expansion has had their share of very long last tiers.
ICC and DS lasted about year, while Sunwell lasted 8 (to be fair Black temple lasted about year because you couldnt replace BT with Zul'aman) - also if you never got to sunwell level then you were stuck in BT for while..
I feel that the sub base is more shakier and trigger happy on unsub/wow-break buttons than ever before.
Can they really get away with year long tiers anymore? Around ICC with hardly any competition on the mmo market, gradually making it easier for pugs to be alive it seemed to be enough to keep people subbed. But I dont think those things will help this time anymore - there is competition on MMO-market and stuff like next gen consoles are coming soon.
I dont wanna go blaming LFR but look, if you can see the whole raid in possibly 2nd week, or inside month of release..why would person like that sub for next 11 months after that?
But to be fair, flex raiding and the possible small patch might help a bit this expansion compared to lest say Cata - but is it enough?
Will we see another "Get annual pass and get.. uuh.. heartstone beta"?