Even with the coming of flying cars, the roadways will still be used, but much less often. In the same way that old cars are still being used today (2008), old cars will still be an option for use.
Likewise, freight carriers – tractor trailers, big-rigs, and very large vehicles will still use the roads on into the next century. Petroleum will still be the fuel of choice up until the midpoint of this century. It will gradually be used less as less after the 2050 coming forth of the new energy.
Petroleum will still be used in making so many millions of products but the new energy of 2050 will eventually replace it’s use in propelling vehicles.
A Psychic's View of . . . 
This new energy source sounds like an answered prayer for all the people of the world who are lacking resources – water, energy, etc. Will this bring about better crops and more water (through desalination – a usually expensive process)? Will it be decentralized or will it be able to be a little unit of energy for each dwelling? And will it be a lot less expensive and dangerous than nuclear energy?
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