Even in five years their will be amazing technological advances, but the question was 100 years. Goal post moving aside, I would be highly surprised if in 100 years energy is not mostly a solved problem. But doom is more dramatic and sells more advertising.
Optimism is great, but we need to plan for the worst, too. The environmental costs for fracking could be unbelievably bad.
Fresh water's one of those resources that's going to become dangerously scarce if we don't manage it properly, and fracking, like oil sands, uses staggeringly large amounts of it. Maybe there's 100 years worth of gas down there, but can we pump water loaded with who knows what chemicals (proprietary mixture, of course) down there for a hundred years to get it out?
Plus, what's a 100 year supply at today's consumption rate could quickly become a 50 year supply if consumption doubles, or 25 years if consumption quadruples. Why would consumption jump so much? What if cars started running on liquified natural gas instead of gasoline? What if power plants switched from nuclear to gas? What if the population grows another 20-30% in the next 25 years?
It's never actually a 100 year supply. Exponential growth will shrink it faster than you think.
