The bubble will never burst. It just reflects the lower productivity of the government funded education program. In fact, as Larry Summers observe, everything that the government touches, from healthcare to post office, is bound to have lower productivity growth and as a result its share of household expanses is going to increase. Maybe until the date that the government is so over-bloated that we are running into $14.3 trillion debt ceiling and S&P threatens to downgrade its AAA status…nah, I take it back.
A segment of the college bubble may burst though which is called for profit education. Steve Eisman is on it (he is one of the few who is famous for shorting the subprime mortgage): http://en.wikipedia.org/wiki/Steve_Eisman