This reminds me of Peter Thiel's idea of "indefinite optimism": we've been spoiled by a recent history of frequent cutting-edge innovation, so we assume that it will continue despite having no idea of the shape it will take. The key here is recent history -- humanity has only been advancing at its current breakneck pace for a few generations. Technological stagnation is more the normal mode.

I think we should consider the possibility that growth in processing power will level out at least for a while. There are some interesting research avenues which may yet bear fruit, but there's no guarantee that some miraculous scientific breakthrough will appear just in time to salvage exponential growth. "Moore's Law" is not some fundamental law of the universe.