well there are 120,000 merchants. but when it comes to bricks and mortar retail stores, there are alot less.
i think bitcoin works best online. such as this latest merchant
http://worldoftanks.com/en/news/pc-browser/31/bitpay-bitcoin-premium-shop/
they have 70million customers so even if 1% decide to look into bitcoin.. thats 700,000
xD I like your precision "but when it comes to bricks and mortar retail stores, there are alot less."
Yeah indeed ^^
But online btc has its success. Probably because merchants already using online payment have already "a foot in the great world of the internet".