Living here in northern Indiana, the home of the big 5th wheel and many boats, we are certainly seeing the downside of the current economy. I personally think that the boat manufacturers are going to be in trouble, because the days of Joe Public affording a gaz-guzzling expensive toy that serves absolutely no practical purpose are probably numbered. Even for fishing, if you factor the tackle, bait,
license, boat payment, motor payment, boat
license, trailer
license, launch fees, lake access fees, taxes, maintenance and so forth, any fish you catch will have an effective cost of probably over $100 per pound, in most cases. Boats have their value in recreation, and in nothing else.
Trailers are different, though. They can have practical uses, as many here on this forum can attest. The RVs we know today got their start in the depression as mobile homes -- not the mobile homes of today, but homes that could actually be moved from place to place without needing a lot of special equipment. This allowed people to own their own home, yet still follow the available work. Now that home ownership is getting tougher for many people, and job stability is going out the window, I think there may be a growing market for truly mobile homes again. If the trailer industry will move away from the current glitzy-luxury-throw-it-out-in-five years mentality, and starts producing affordable, durable, practical live-in-able trailers, I think they'll have a solid future.
By the way, yes, a high-up person in one of the local major RV companies said the target lifespan of their big 5th wheels is five years. After that, it goes into high-maintenance mode.