Why are you assuming the "algorithm" just includes the finance bits? It also includes the people involved (mentors, investors, community). Why wouldn't that be replicable in other cities outside the Valley? As long as they have both the financial capital and the social capital I don't see why it couldn't be successfully duplicated.
TechStars seems to be doing well in Boulder and Boston. Seedcamp seems to be doing well in London. Launchbox seems to be doing pretty well in DC. DreamIt seems to be working well for Philly. Someone could do it in Chicago (or any other moderately sized city with some semblance of a tech community already, some willing investors (or the ability to attract investors from other parts of the world), and a few nearby universities) with the right network.