If it's the newer romex with plastic covering then it should last around 100 years without problem.
If it is romex with pvc covering then I wouldn't worry about it. The copper wiring itself will last 100's of years it's the covering "insulation of it" that is what breaks down over the years.
If it's still in good shape then I'd just leave it be. No since fixing something if it's not broke.
Rewiring a house can cost thousands and walls will probably have to be torn into to get at the wiring.