It's a fairly basic question, for a not-so-easy answer. Regardless of which expansions you loved, or hated, what expectations / story lines would make you stay or resub? Or, are you happy with the current model and would love to see Blizz make another expansion with the power and story of MoP? (SORRY TO NOT INCLUDE 55 DIFFERENT OPTIONS TO ENCOMPASS ALL OPINIONS)
As for myself, I am currently unsubbed, uninstalled, and even had my account locked and characters deleted as I was uninstalling. IF the next expansion is truly, beyond words amazing, I would consider repurchasing the game at its entirety and resubbing. But the story would have to be amazing, the gear would need to be outstanding (and not cheap chinese knock-offs), old models need a new look for ALL of the original 10 races (including TBC), and the story needs to be EPIC (like Sargeras, or Emerald Dream).
I want to play again, and I want to be enamored like I was in TBC. That's just me. How about you?