Aside from the condition of the string deteriorating a little? Yeah. Your downrange groups will open up a couple inches. Might not be noticeable much at 20 or 30, maybe 1/2" or 1" which people tend to attribute to shooter error, but at 40+ it will certainly become noticeable. For me, I want the arrow to go exactly where I'm aiming.
I also spine and spin test my arrows. A shaft that is a bit out can miss an inch or even 2 at 40 yards. So an old arrow and an old string could have you missing the bullseye 4" at 40 yards. I wouldn't feel good about myself taking equipment like that out and trying to shoot an animal with it
I don't see any changes in my vertical in 6 years. You get your bow at the same place I do and I know they mark all bows with white paint so that you can see if something stretched/moved. My marks are in the same place kissing the string like they did 6 years ago when Ray put them on.
Now the crossbow is much easier to detect if something is wrong because you sight it in from a complete rest, eliminating shooter's errors. It basically should hit where you aim. 3 years and once I sight one distance all other are still dead on.