I would never give or sell someone something that was not archival. That is supposed to be a given, and for a lot of good reasons. I had a friend that shared a painting studio with and she got sued for a sizable amount of money because a piece she sold fell apart in short order due to poor workmanship and non archival materials.The buyer won the case too.
Yes, all things are impermanent (not most), but if something is sold as "art" it is expected that the maker will be using the very best of archival materials, or it needs to be clearly stated that they had no interest in that aspect.
Instant film has a lot of major flaws. Usually poor image quality, no negative, so what you get is all you'll ever get, wacky colours that very quickly fade, poor ISO selection, poor permanency, and you have to use plastic cameras w/ limited features or have a camera that can take a special back. The cost per image is astronomical for what you get too. Great concept, poor product. Why doesn't someone reintroduce printing out papers? As much as I dislike the kickstarter business model, I might be interested in that.