Too many variables to give any sensible answer. Some tough old components and bikes seem to be destined to be ridden by huge cockroaches long after humans have all gone away. Some finicky things seem pretty disposable.
Some of the most expensive things are pretty robost. And some of the most expensive are the lightest and most fragile. Some cheapo stuff is over-built and will last forever. And some cheapo stuff is crap that does not work out of the box.
And then you have the variable of how they are used and stored. An X-mart bike left in the yard for a while is not long for this world. But its not uncommon for bikes to be bought on a whim or a hope and then hardly used and then hung in the garage. They last a long time that way.
But, setting aside the extremes of all these things, it seems like a bike and easily last as long as one wants it to.
j
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Cross Check Nexus7, IRO Mark V, Trek 620 Nexus7, Karate Monkey half fat, IRO Model 19 fixed, Amp Research B3, Surly 1x1 half fat fixed, and more...
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SB forever