Depends on what viewpoint your coming from, but from that of a software developer there are
many alternatives that have been much better than San Francisco for years, especially Seattle
https://www.codementor.io/blog/best-cities-software-engineer..., which is also set up for future success as it keeps building
http://www.spur.org/news/2017-06-15/keep-building-oakland. Honestly, I think what we are seeing, is a shift from technology companies, to technology simply being in everything, reducing the usage of such an odd concept as "Silicon Valley". For example: the biggest "Technology" company recently in Seattle is Amazon, a store first - that leverages technoloy. Even the recent things coming out of Silicon Valley have been similar (uber - taxi company that uses technology for efficient trip planning with customers, all the food delivery startups, etc). As we move more and more in this direction, where the startups are X (with technology!) it makes sense for the product to be developed where X is best instead of where technology is best.