As for bindings, I'd say the same thing goes for them as for boots:
If you leave them in your garage or attic and they go through a million cycles of freezing in the winter, and being 90F in the summer, they probably aren't going to last too long. If your idea of "adjusting bindings", is messing with a screwdriver until your foot fits in them, and you think DIN settings are supposed to be up as far as they can go....the bindings probably aren't going to work well or last long.
If you keep your stuff at room temperature, inspect it, and take care of it, it'll last a long time. As for boot liners wearing out...they tend to get "colder" after that period of time, but don't exactly develop holes instantly or whatever.
Personally, I ski on Nordica NR981 boots from 1990 or 1991, they're the best fitting boots I've ever felt, and cost $5 on ebay to get a spare pair for new rubber heels. Still working great.
Wish that would work for me.../cry. I skied my N981's since new in in 1991. The right one finally gave up the ghost just last Sunday as I was pulling it off after the last run of the season here. Cracked from the back grip plate up towards the cuff about 7 inches. 19 years and too many days to count. Heat molded insoles at the purchase and they never needed anything else. You can guess what brand I am looking at for thier replacements...
R.I.P 981's
Luithien