I would not back out of it, if it would become free to play.

What I would dislike at an f2p ARR. The possibilties of it evolving will be slim to zero. I don't exactly know what happened to Aion. I don't know how it is faring atm. But if I would have bought that game, been a payiong customer, and than the (for me) sudden change. I would have been annoyed.
Why I would not back out? Because I love the world and the loving detail of everything.

You know, it is easy to say "If you can't afford 15 a month, you have other problems" lets put it nicer "If 15 are to much for you per month for a game, you should maybe get your priorities straight"
For me, I quit smoking, buy cheaper but not cheap food, so I can sustain the hobbies I like and quit hobbies I cant currently afford (bye bye 2/3 FFXI accounts)