One would have to be able to quantify future revenues to answer your question, but based on the slope of the production curve for natural gas, it could go on for a few decades.
That is not an advocation of the process,its just the way it is shaping up.
Future revenues are never a given in the Oil and Gas industry. They are price dependent, and also rely on depletion being replaced by new production.
The current surge in production is due to increased drilling and extractive technologies, but in the absence of new drilling that could change.
Figure gas wells commonly deplete by roughly 7% annually (some more, some less). While depletion (without new drilling or recompletions of existing wells) will cause price increases, people will reach the point where they'll burn the furniture to keep warm rather than pay more than they have (laffer curve).
Increased costs in manufacturing, electrical generation, and chemical feedstocks will affect a broader market sector, and the costs would be passed on to consumers.
At some point, an administration hostile to the production of our own energy will not be able to feed off of that, and the decline in Federal royalties created by depletion on existing wells and de facto moratoria on drilling new ones on Federal leases creates a situation which is fiscally unreliable.
Compound that with less disposable income after inelastic demands for heat and power are met, and the economic malaise becomes endemic.