Of all the chemical color print processes, Polaroid instant film is the least stable by a large margin. Not only does it fade faster than any other color print material in the light, but in dark storage, because of residual chemistry from the development process, it will stain. The only way to preserve Polaroid prints is to place them in cold storage, which slows the chemical staining.
All the large Polaroid prints sold as fine art prints are made from the same commercial material as the boxed instant print film. The large cameras use the commercial film off of the large, manufacturing rolls before it is cut down to commercial sizes.
Henry Wilhelm has had accelerated fading projections for Polaroid material for decades. My recollection is that most Polaroid film exposed to 12 hours of indoor lighting (incandescent and fluorescent, but not daylight) at room lighting levels will show noticeable fading in 7 or 8 years.
Here is link to Wilhelm's monumental book on THE PERMANENCE AND CARE OF COLOR PHOTOGRAPHS. You can down load the entire book or chapters in PDF format for free from Henry's site:
http://www.wilhelm-research.com/book_toc.html