Since the subs dropped so much that Blizzard decided to stop telling us the numbers and the game subs are in a steady decline since 2011 (that if continues at identical pace would mean no more subs in 2019 - but we will reach the hardcore-fans plateau before that) I wonder when WoW will go F2P.
All signs are already there. Money to buy gold, Money to buy instant level 100, level 100 trials in Legion, money for cosmetic items like pets mounts and three hats are all already in the game. All that is missing are few more crafting- and xp-boosters for money.
I think if WoW would go that path they would continue to offer the regular subscription just like SW:TOR offers (where you get free tokens to buy boosters each month).
This would increase the numbers of players significant. It even worked for failed sub-MMORPGs and made them lucrative enough to run for years. Rift for example (they had 1 million subs in 2011) is still running.
What do you think, how many sub-only expansions are we looking at? I think Legion could already be the last one.