Since Thor has owned Airstream since 1980, I guess folks need to go back 34 years if they want a "legendary" model...
To some extent this is largely irrevelant. Airstream is still considered the pinnacle of travel trailers, the gold standard that others look up to, and the choice of affluent owners that want the iconic look, timeless shape, and name recognition that speaks luxury and quality. And, today unlike before the Thor ownership, Airstream partners with Mercedes that has all the same name recognition as Airstream has carried forward since the mid 1930's. They may not be legendary nor the same company but they still are associated with the best, cost the most, last the longest, and are bought by the most descriminating.
Maybe in 80 years we can see how many Forest River or Keystone products are still on the road. Airstream's number is over 60 percent. Pretty impressive really regardless of who builds them.
Kind of like Harley Davidson that was once owned by a bowling pin manufacturer. Harley through all the tough times and more than one owner never lost it's reputation and luster for what they stand for. And you did not mention that prior to Thor, Airstream was owned by Beatrice Foods, hardly an RV manufacturer! But, the timeless design and original commitment to quality instilled by founder Wally Byam has stood the test of time.