Well, the relevant factor in that analysis is energy return on energy invested, and two factors are currenly helpful. The cost of energy has dropped which makes complexity more affordable - at least for the present, and we are rapidly building the most energy efficient renewable source of electricty currently available - wind, followed by solar. If we continue on the current path we may lock in enough sustainable, renewable energy to make un-affordable fossil fuels irrelevant as an energy source. And, while EROIs of 100 are no longer attainable, the EROI of wind and solar seems just adequate to our needs and to support complexity close to what we have.

Mostly we just have to stop being so stupid in how we use our resources. That is the real challenge, along with appropriate distribution of wealth. And overriding all of this is the importance of climate change - which has to be slowed and then reversed.  

"It is not necessary to have hope in order to persevere."