LNG is being seen as the future in a lot of larger horsepower applications, such as ships, ferries, tugs, and supply boats, as well as power plant back-up power generation.....but I just don't see it in the RV industry, unless they can come up with a more convenient method of filling the tanks. With gas/diesel, you have multiple choices in almost every small town in America.
I just don't see that happening with LP.
I do believe that wind and solar have future applications, if the prices come down, but as mentioned, it's not going to run your RV. Maybe a few panels or a small windmill to operate the television or inverter... but not much else.
I see it at your stick-built, but not the RV.