The future potential of shale gas depends on the price of the gas being sold.
As gas becomes more abundant, via horizontal drilling in shale, the price will rise very slowly or may decline.
If that happens the operators( thru lack of activity )may lose their non-productive leases and the millions spent on acquiring those leases becomes an added burden to the profitability of the projects.

I suspect this is why many of the operators are hedging their bets by selling off interest in their large leaseholds.

Pity the buyers who haven't figured this out.

"The wisdom of an old geologist who has 60 years experience in these games".