I think the answer is yes, the shale industry is a big part of where jobs are coming from, they start losing money, people will start losing jobs and the oil will start going for less meaning the companies will start losing money. The oil business is normally a high paying one.
The manipulated market that has made oil so cheap is a mere smokescreen around the fact that our own energy production is being shut down. The price of energy is therefore increasing as a result of this shutdown. With no alternative energy source widely established, and clean coal factories being shut down in favor of using dirty coal factories in countries such as Mexico and China, the standard of living in the U.S. is set to be lowered dramatically.
Yes, I think that if the U.S Shale Industry shrinks by 30%, the economy will be in trouble because the economy is already going downhill so much that I think this would just be the icing on the cake to a kill of economy. Everything going on is killing it even more.
The shrinkage of the shale industry will be devastating for the individuals involved in mining shale. It could hurt entire areas where shale employed many people. The economy in general, however, will soon bounce back. Industries rise and fall all the time, and something else will come up to balance out the effect of the shale collapse.