Such claims are ridiculous. Nobody needs burning fuel. Everybody just needs energy and it does not matter which is its source.

If enough energy is produced by other means than burning fossil fuel, nobody will return to the past.

I happen to be one of those who does not use directly any kind of energy, except electrical. Despite the fact that I am still connected to methane gas distribution, I have never burned it for already around a decade. (And unlike most, I cook myself from raw ingredients everything that I eat, but I stopped using flames for that many years ago.)

If burning fossil fuel would stop completely right now, that would not affect me at all, much less would return me centuries in the past, as long as the electrical energy supplier has enough sources in its hydroelectric, solar, wind and nuclear plants, all of which are abundant where I live.

For aircraft and spacecraft, hydrocarbon fuel will remain the best solution, but synthesizing hydrocarbons was already possible at large scale before WWII and it could solve easily this problem in a CO2-neutral manner, if a fraction of the money wasted for various useless or harmful things would be invested in improving the efficiency of such critical technologies.

Most people can't afford to go 100% electric.

Many of them are already sacrificing health care to afford food and shelter.