Scott Galloway, a professor at NYU's Stern School of Business, made waves this week when he predicted that tech giants Amazon, Apple, Google and Facebook would all be extinct within the next 50 years. He cites how of the Dow 100 stocks from 100 years ago, only 11 have survived, and how a much faster business cycle nowadays would speed up the extinction process.What do you think? Do you think any of these companies will be out of business over the next several decades? Which one?