Dave, you're being overly pessimistic again...
The end of the world is nigh! Or
The voice of reason...
We have a serious fuel crisis looming, but it is just a question of common sense finding a solution. Every square meter of earth receives 1kW/m^2 of sunlight. There is enough coal to last another 200 years. Nuclear fission exists as an interim solution with fusion on the horizon.
Alternately we could collectively bury our heads, continue to ignore concerns about mpg of SUVs (the ones that don't actually go off-highway), and mindlessly ignore the kerosine requirement of passenger jets.
My own view is that us engineers will have to find a practical solution. The first is to convert other viable energy sources into liquid hydrocarbons. Forget all this hydrogen nonsense: all heavy lift rockets use liquid kerosine for stage 1, since it has the highest energy/volume figure (the exception is STS SRBs using ammonium perchlorate and aluminum). Rockets are extremely weight sensitive, so helicopters must be better using easily pumped diesel/kerosine.
However research into methods to improve helicopter aerodynamic efficiency are also a very practical solution. You were championing Independant Root and Tip control for rotor efficiency.
Besides with CO2 induced global warming, i have the feeling we are going to be seeing a lot more helicopters over flooded regions...
Mart