There is certainly a shift up the swag to caravan progression taking place, just have to look at the manufacturers to see that's what is happening. I think a couple of the things that play into this are the baby boomers are getting older/softer and they are hitting retirement age so happy to spend the larger amounts required for a caravan from their retirement nest egg, to buy something to fulfil lifelong dreams of travelling, also with modern manufacturing techniques, the price of luxury caravans are within reach of a lot more.
I think some factors that make it seem bigger than it actually is though, the vast majority of camper trailer users wouldn't think about going on a forum about them, it's more "enthusiasts" on here, and they are more likely to spend the money to upgrade as getting away/traveling is more what they are into, also, as you get older, so do people you know so it increases the likelihood of people you know moving to van's.
There is a definite shift but how much of that is due to the ageing population and the typical preference for comfort that comes with it, and how much of that has to do with a general shift in the market is hard to quantify.
