In the long term, what Bay Area / Silicon Valley has, while the other metropolitan areas haven't, is its culture. Specifically, it is the combination of its entrepreneurship at every corner, its ambition to challenging incumbents, its huge talent pool.
IT industry will collapse or dramatically shrink some day. But this culture wouldn't in the forseeable future. Besides IT, it is also one of the centers in biopharmaceutics, alternative energy, electric cars/auto-drivering vehicles, food industry, etc. Although nobody knows what is the next BIG thing, it is quite possible it will get BIG in SV, if not born here.