I can appreciate that selling a rewire in an old house has its challenges. I'd caution That assuming the wire is in good shape because it is flexible where you can get to it and thinking it is in the same shape where it is concealed is a dangerous assumption.
It is just impossible to predict an ultimate failure date as there are just too many variables. Sure the copper should last thousands of years but the insulation has no millenia of data to show its mean failure.
Sparky from your post I am assuming that you don't know that arc fault breakers have ground fault protection built in. It is not GFCI protection and trips around 30 milliamps instead of the 6 MA for GFCI protection.
