I think the simple fact that the Babyboomer generation has started to retire and will continue to do so for next several years, will cause a huge spike in RV sales and advancement.
I can see the trend getting "bigger and better" while fuel stays low. But if fuel goes up and stays there it will effect the RV development.
We use a CG in central Illinois that keeps about 22 of their sites open all winter. They have frost free heads on their exposed water outlet for each site. They simply cut the top off of a plastic 55 gallon drum, install a heat lamp inside, and turn if over on top of the water outlet. Of course anyone using one of these sites has to utilize a heated water hose.
As horrible as last winter was they never had any water lines freeze up. It may be a slow progression, but I think you will see more winter camping spots open up.