Already well underway. I know a company that is doing quite well converting commercial fleets to run on LNG. Between the lower cost and the cleaner burn, resulting in less engine wear, the ROI is pretty dramatic.
When I told my Uncle that we were working on it he said: “That strange I did the same when I went to Michigan 30 years ago.”
The economics and infrastructure were just not feasible at the time.
Now with fracking it looks more promising.