It's a safe bet that most blue-chip companies with stable revenues and time-tested business models will be just as big, if not bigger in 10-20 years. They'll ta

It's a safe bet that most blue-chip companies with stable revenues and time-tested business models will be just as big, if not bigger in 10-20 years. They'll take a hit when the economy inevitably enters the bust phase of the business cycle, but people will still be buying shoes and coke. It's the PE of companies like Facebook and Twitter, who derive their earnings from questionable business models (notoriously hard to measure ROI on advertising, millions of fake/spam accounts, possibility of disruption ala Myspace) that I would be concerned about.