My prints are produced with archival inks and papers. With proper care, they should last for many decades. Wilhelm Imaging Research, which tests the archival characteristics of many paper and ink combinations, released in early 2009 new ratings for my printer, the Epson 9900 (warning – PDF file). Framed under glass and with Epson papers, longevity ratings ranged from 68 years to over 100 years. With UV glass, the ratings increased to a range of 98 years to over 200 years. While such testing cannot predict the future with certainty and each paper and ink combination needs to be tested separately, you can be certain that when properly handled your prints will last longer than any traditional color process.
So, how do you handle the prints properly? When framing, use archival materials and UV-protective glass or plexiglass and keep the print from contacting the glass. When storing outside of a frame, place in an archival envelope and do not place the prints in direct sun (archival albums are best). Basically, treat your prints the way you would treat any other art that you value and they will last a lifetime.