The actual, minor convenience additions they are looking at adding? Pretty good chance of having minimal backlash, at least from those already loyal to the brand (the OP's suggested set would cause far more backlash with a sub still in place). Those of us who have moved on to other brands, or are on the fence, may be quite a bit more critical of the move.
Right now the $15/mo is a good value (for the most part), but they can't push it too far. Add too much as cash shop only items, and you reduce the value the customer is getting out of their subscription. Reduce that value too much, and while you will have loyal customers that will stick around, you absolutely will lose others as they decide they can get a better deal in other games (which I suspect is already happening for at least a portion of the MMO market). To combat those losses financially, what would they have to do? Put even more in the cash shop to generate additional revenue. Lot of risk there, and with subscriptions having fallen almost continuously since late 2010, I doubt Blizzard is willing to go for too much risk (fortunately).
I don't think other games would follow suit. Even Titan is unlikely to be a subscription based game, and the overwhelming direction right now is to some sort of either subscription-less or hybrid (not required, but subs get extra perks) model. The Secret World actually tried it at launch - cash shop with a lot of cosmetic items - and got slammed for it. Blizzard's the only one with the clout to pull it off, and only if they don't push too far.