My jeans wear out eventually without experiencing much shock load, just normal wear and tear, so I'd bet saddles do wear out eventually, but with the amount someone like me uses it, likely not for many many years. I've hunted pretty hard out of my original method, particularly in late seasons it seems. I wear it in 100% and out 95% of the time I'm walking around in the woods, and I am starting to see some minimal wear in the seams where things come together, like the first stitch has stretched slightly, and some pulling of threads from the occasional edge. The clips to hang the lower half were crap, broke and I replaced them with a simple molle strap. I have no qualms continuing to use this saddle, it looks/feels just as robust as when I purchased it, however it is slightly more flexible than new, and from what I understand that means the fabric is "broken in" and therefore theoretically weaker, but still well within safe.
All that said, in my opinion expiration dates largely come down to avoiding litigation and liability- if your saddle manufacturer advertised a lifespan, it doesn't mean it will definitely fail, but it does mean that if something happens and you're past that date, you or your estate has no ability to sue them for damages, as you were using expired gear. Ropes I'll replace on a schedule even if visual inspection is ok and they pass the pinch test, I went into detail on that in my prior reply, saddles I'll continue to visually inspect and use. Though my desire to try something new and need to admit to myself that I do actually experience hip pinch in my method but just have a high pain/annoyance threshold so ignore it... May be actual reasons to replace. Or try the drey I bought but never gave a fair shake.
All that said, in my opinion expiration dates largely come down to avoiding litigation and liability- if your saddle manufacturer advertised a lifespan, it doesn't mean it will definitely fail, but it does mean that if something happens and you're past that date, you or your estate has no ability to sue them for damages, as you were using expired gear. Ropes I'll replace on a schedule even if visual inspection is ok and they pass the pinch test, I went into detail on that in my prior reply, saddles I'll continue to visually inspect and use. Though my desire to try something new and need to admit to myself that I do actually experience hip pinch in my method but just have a high pain/annoyance threshold so ignore it... May be actual reasons to replace. Or try the drey I bought but never gave a fair shake.