Sorry to burst your bubble*.
Shops go out of business because the product being offered is not desirable or needed. In this case, small shops (as you put it) don't succeed because the heads that they are making aren't good enough to sell.
Thus no matter how many of these small, failing shops you accumulate, the "Mastersty" (as you put it) will invariably not succeed because the quality of textures being produced won't improve. Simply putting everyone's heads onto one shop will not increase the desire in a customer to purchase something - the sheer number of items being displayed might actually reduce their chances, depending on organization. The most that you'll achieve is to compile all the small threads that I need to look through into one large thread which I need to read through. It's a classic case of quality vs. quantity.
In addition, joint ownership often leads to disputes between owners over splitting of profits. This will probably just be further aggravated if you continue to introduce people into the shop. Who's to decide how profits are split? What prices are? Who gets to own and edit the thread? I don't care how hard you try: people are going to disagree, and it probably won't end well for anyone involved.
*hanz0 does not feel remorse for bursting your bubble.