It's a good theory but I think the investors are pretty straight-up about wanting their companies on a short leash.

The key will be those other cities/hubs having their own successes, bringing in the capital and expertise to nurture new talent. It's likely that the number of successful hubs that can be supported is pretty low. I happen to believe that the amount of (awful word) synergy needed to flip a few percent of startups from fail/borderline to success is pretty high. In other words, all those know-a-guy-who-can-help connections have to have a high concentration before it starts to pay off.

But then mine is just a theory as well and has a high chance of being wrong.