A lot of people still think it's possible to have an energy transition, even those who should know better and are very well aware of the decline of oil resources - for example, Dennis Coyne who runs Peak Oil Barrel. He knows very well, because he's made mathematical models to that effect, that oil production could decline by about 1/3 by 2050. But he thinks a transition will occur by then. I think it's a religious-like belief at this point that there has to be something waiting in the wings to save us. Oh, and the mainstream opinion is, by the way, that oil supplies are plateauing because of lower demand (because of this alleged transition) and not because we are depleting the main sources.
On the other hand, you have guys like Art Berman who think supplies will last a good deal longer but that there will still be enormous upheaval in the coming century. Out here on the fringes there's not much consensus.