Brew on premises (BOP) shops are not all that uncommon (there are a couple of all-grain BOPs here in Portland), but they usually don't do all that well. Most of them charge in the $100 range for a 10 gal batch. The up side to it is that they supply all the ingredients and equipment, the recipe, they do all the cleanup for you, and there's always a pro around to field any questions you might have. The price being the only real downside to the customer. The reason they don't ususally do well is most homebrewers are (by nature) do-it-yourselfers. We don't want to spend extra money for something we can do ourselves. We don't mind cleaning up after ourselves, we don't mind building elaborate Rube Goldberg type contraptions to make our beer, and we CERTAINLY don't mind learning all there is to know about germination, isomerization, fermentation, etc... etc.... for our craft. It's what drives us.
I think they are great ideas for people who live in small apartments and don't have room to brew. Also for a new brewer who wants to start with all grain, but doesn't have the equipment yet. You can learn from the 'pros' and decide if you like it enough to make the investment. They are also sometimes used as team-building experiences for business.
Our beverage that art in kegs,
Hallowed be thy tap,
With thee supplied, we will imbibe,
At home as we do in the public house.
Give us this day our liquid bread
And forgive us our spills
As we forgive those who spill upon us.
Lead us not unto hangovers
But deliver us from overindulgence.
Buy a man a beer and he wastes an hour. Teach a man to brew and he wastes a lifetime.