While in the past, most companies grew under the direction and helmsmanship of a corporate suit A-list CEO, the return on investment is no longer there: 20 years ago, investors in a million dollar startup would get nervous and push for an MBA to steer the ship. When Google got big, there was a lot of clamoring from investors for "adult supervision". In contrast, while there were a few calls for Zuck to relinquish the helm to MBA-led adult supervision, he has resisted them while successfully growing his company to apparently a 50-billion dollar valuation. I only expect this trend to continue. The next big tech startup will never have a corporate non-tech type at the lead until it reaches it's current-day Microsoft-esque peak and slow decline. (One can argue that this is already the case, given that Eric Schmidt is actually a tech geek in corporate clothing.)
And this effect is not just at the top CEO-level: it is mirrored across the slightly lower tier of upper-management: the very tier that most aspiring MBAs hope to occupy at the pinnacle of their career. High performing tech departments are no longer being as gingerly managed by MBAs --- or if they still are, the leadership and powers are slowly being devolved more and more to the nerds. Quant managers in investment banks are already more compensated than the CEOs of those banks themselves. People no longer blink in horror when a boffin (what an antiquated and obsolete word!) is made a CEO.
Of course, most _mature_ well-established companies are and will probably continue to be run by MBAs in well-oiled corporate boardrooms. But the compensation is not the same for someone who takes a billion dollar company and grows it at 2% year on year as it is for someone who takes a 100 million dollar company and turns it into a billion dollar company.
In the past, MBAs used to be handed on a silver platter these gems in the rough by nervous investors eager to get some security (imagined or real) in their growth assets. This is no longer the case. And therefore, MBAs no longer have this easy source of high growth opportunities to lead to success. They are going to have to make these gems in the rough themselves, because those who are making the high growth companies are not relinquishing control (like Zuck.) to them to steer and get lavishly compensated for.
And if there's anything I've learned from the tech industry, it's that MBAs don't create value, aren't original, and don't actually start things --- and they are finally losing their cash cow of having high growth ventures handed to them. I wouldn't be surprised if in 10-20 years the MBA would either be radically different (evolved into a little corporate training and social skills for nerds seminar) or obsolete and viewed as a mature, well (but not outrageously so) compensated professional training programme like a degree in Accounting or Medical School. I have even bet on this being the case in choosing CS grad school over an MBA program in the recent past.