If cables can break-in, can they then wear-out?

OK!! I have had more than one speaker cable 'go bad'.
Monster (long ago in a galaxy far away) tarnish so bad they became a throw-away. AudioQuest Midnight cables the dielectric covering on the wires failed after 15 years or so. Stick with a teflon coated wire!!!!
I still use some home made Levinson wire cables I made nearly 25 years ago.
The culprit is the dielectric coating on the metal. Good coating equals: last for a really, really long time. Poor coating or one that will degrade equals: bad.

No they will not wear out if they are not abused or exposed to a detrimental environment. Break in is for real...unless your deaf of course IMHO

Yes.

Nothing lasts forever!

But cables should last a rally long time though. Our ears will probably go up first.

As a former test equipment calibration lab tech, you'd think I felt measurements were everything, but I have seen far too many components (cables included) that measure EXACTLY the same with steady state signals sound vastly different with music.

Now I just repair gear praying I don't change the original equipment sound whilst doing it.

I think we do not yet know WHAT to measure to ensure a particular sound. Years of measuring have given us a pretty close approximation, but something is truly missing in our gear or our approach.