RE: There is only so much natural gas, once its gone its gone.
You might want to open your mind up and consider other theories:
Are we sitting on unlimited fossil-fuel resources?
http://hotair.com/archives/2011/06/03/are-we-sitting-on-unlimited-fossil-fuel-resources/
If gas hydrates as well as shale gas, tight oil, oil sands and other unconventional sources can be tapped at reasonable cost...
That has proved to be a rather big IF.