80k is a lot. You can grab a 44ft KZ for 65k or less for the most part and be fully loaded. Same with most of the other stuff in that price range. There isn't much of a reason to pay much more than that honestly. We've owned the "high end" fifth wheel and were not that impressed.
Make sure you visit these units and see what you like. There is a world of difference in a fifth wheel and a travel trailer. Much less an Air stream. Don't get me wrong, I appreciate the materials and craftsmanship I just find the units themselves to be lacking in livability compared to other units.
While you can't argue that aluminum will out live fiberglass the bottom line on these units is they will last as long as you are willing to keep them up and look at them. Most of the people aren't trading or getting rid of their units because they are falling apart or POS. They are getting rid of them to upgrade to the newest and greatest. There have been tons of advancements in floor plan layouts, electronics etc over the last 10 years and if you shop for older units or have been RVing awhile you know exactly what I'm talking about.
The options we have today are plentiful compared to what was there not so long ago.
Personally, I'm not interested in Air streams as the layouts aren't very good IMO for livability long term. Nothing compared to other fifth wheels or even other travel trailers. So that would lose me right there. As for the other brands, they'll last as long as you're willing to look at them.