One of the things mentioned at Blizzcon was that Blizzard donated $1.1 million from the sale of the Pandaren pet to the Make-A-Wish foundation. That's great for the Make-A-Wish foundation, but I'm not sure what it says for the viability of item shops.
$1.1 million sounds like a lot. Blizzard donated $5 from each Pandaren, so we can infer that 220,000 people bought a pet. Sounds like a lot. But Blizzard has approximately 4 million subscribers across North America and Europe. So just 5.5% of Blizzard's subscriber base were willing to pay for this pet, even though a significant portion of the money went to charity.
Blizzard would have to sell *27* items of equivalent appeal just to make the money they make from one month of subscriptions.
This is the part I just don't believe about F2P and item shops. Every indication I've seen suggests that only a tiny fraction of the potential audience is willing to pony up money if they aren't forced to.
I just don't think that games where 5% of the players support the game and the other 95% just leech can be financially stable enough to thrive.