I'd probably only unsubscribe if they replaced all dailies Timeless Isle/Battlefield Barrens type grindfests.
On the other hand, if they make it so you can get faction rep by doing dailies, dungeons or grinding, and the dailies unlock story like in 5.1, I'd be subscribed the whole expansion. I don't really care if they make it so you can only earn say 1,000 rep per day with a faction, total, from any of those methods. Personally, I like the dailies. But I understand some people want options, and if Blizz doesn't want people being able to grind to exalted in one day, it shouldn't be TOO hard to just make a daily limit for the first couple of content patches.
Oh, and no gear behind faction locks. Just mounts, pets, profession recipes for toys etc.