Sounds fishy to me... if done authentically, a trailer from that era would obviously require building all new 7-panel endcap tool and dies (or locating the originals, if they still exist) as well as reverting back to older dimensions (heights, widths, etc).
Why reinvent the wheel by "building from scratch" when there are plenty of 59-60's out there to refurbish? And if Airstream would put that kind of expense and time into building TWO one-off trailers??? Well, that would certainly make me question their business sense for such limited nostalgia.
Still.. a neat idea. I like the idea of a widely available, limited ed. 13 panel trailer... new from the factory. Could be really nifty, though it would
never outshine the quality than people like Winick, Uwe, Frank, Timeless and others can turn out in their shops.
I'd also seriously question whether or not a 50's trailer would be legally roadworthy to build new - headroom, lighting locations, little stuff the DMV requires. Restoring an old one sidesteps all that, being that it's more or less grandfathered in... by virtue of being built by our grandfathers.