Upheaval and short-term stresses, certainly. I think it would be worth it, however, if a totally clean, limitless source of power were discovered. Providing, of course, that it could be properly controlled. I don't particularly want my crack smoking next door neighbor to have a fusion reactor in his basement.
Anyway, if you've been following the latest rumblings out of the climatology world lately, we are likely fast approaching a climatological "tipping point", past which regaining control over climate change will be nearly impossible. At the same time, as massive markets open up in Asia and elsewhere, we're looking at millions of new drivers in the next few decades. Our dependance on oil as a source of power will be our undoing. So it was written in the great book of Shabu; so shall it come to pass.