Geoffry,//first, shale gas is primarily filling in gaps in gas production left be the decline in conventional natural gas output. Conventional output hs aleardy peaked.
I do not consider the last word on natural gas to have been said. Yet even if we discount all of the other arguments against natural gas being disruptive, in order for natural gas to be truly disruptive, it must be possible to produce enough natural gas to replace a substantial amount of coal and/or oil. It is by no means clear that the replacement of other fossil fuels by natural gas will be possible. Douglas B. Reynolds and Marek Kolodziej argue that natural gas production in the United States and Southern Candida will peak in 2013. http://www.mdpi.com/1996-1073/2/2/269
The Canadian natural gas industry reportedly has already reached its peak production. http://peakoil.com/production/canadas-peak-natural-gas-crisis/
Although the EIA projects increases in natural gas production at least until 2035, the EIA projections suggests that the the production will only be 10% higher in 2035 than it is today. The Post-Carbon institute reports "Even assuming the EIA forecast for growth in shale gas production can be achieved, there is little scope for wholesale replacement of coal for electricity generation or oil for transportation in its outlook. Replacing coal would require a 64% increase of lower-48 gas production over and above 2009 levels, heavy vehicles a further 24% and light vehicles yet another 76%. This would also require a massive build out of new infrastructure, including pipelines, gas storage and refueling facilities, and so forth. This is a logistical, geological, environmental, and financial pipe dream."http://www.postcarbon.org/report/331901-will-natural-gas-fuel-america-in
This is hardly disruptive as far as fossil fuels substitution is concerned. Thus it cannot be said that natural gas will replace other fossil fuels during the coming decades. The need for disruptive energy technologies still exists, and has to be included among energy goals.