Le Fanu said:
I think the cases nisaba mentions - of brittleness & eventual shattering - must be extreme cases, surely, after centuries and centuries. My guess is that all these wonderful historic decks in the Bibliotheque Nationale, Paris and British Museum etc were on very primitive acid-free/bleach-free paper and have aged in exactly that way which some of us rather like.
In her post she was talking about books published in the 1970s.
Acid applied to paper to whiten it is a recent phenomenon. It will yellow with age, though for decks and cardstock, who knows how long it will take? But anything cheaply printed from the 1970s to today I wouldn't give more than a century or two under normal storage conditions. They will last much longer if well cared for, but they are made with recent "advancements" (that really aren't advancements) in paper technology.
Newspapers from a couple of decades ago crumble because of the acidity in the paper.
Newspapers from the 18th century are quite sturdy because of both differences in papermaking and because of the fact that acid was not deliberately added to them to make them white. Though there is some natural acidity to the paper printed on. It yellows of course, but does not crumble.
I know, I've worked with newspapers of varying ages at my job, it is interesting to see how well the older ones hold up compared with those of the last few decades.
So yeah, the older decks will last a good long time. Recent ones, I doubt they will last nearly as long as the visconti ones have already unless they are stored under very good conditions. There are methods for de-acidification of paper and cardboard as well, but I don't know how that works or if it would even work for something like a deck with the gloss added to it, lamination, or certain types of ink.