[ganjianwei]

Technology as an industry is different from verticals such as cars, books, etc. This quote by Mark Andreessen in an interview with Charlie rose sums it up well:

"The core idea we have, the core theory we have, is that the fundamental output of a technology company is innovation and that's very different than a lot of businesses, right? The fundamental output of a car company is cars. Or the fundamental output of a bank is loans. The fundamental output of a tech company is innovation, so, the value of what you've actually built so far, and are shipping today is a small percentage of the value of what you're going to ship in the future if you're good at innovation." Source: http://www.businessinsider.com/marc-andreessen-on-charlie-ro...

If you believe that Silicon Valley is good at innovation, and not just software, or hardware, or social networks, then by definition, it will continue to be the hotbed of economic activity as specific verticals die out or get disrupted.