Whether a tree is grafted or not has nothing to do with fruit production or quality of fruit. Trees are grafted to produce stronger, disease resistant trees. The root stock depends upon your growing area and what the challenges will be.
If your friend's tree is declining, it wasn't grafted to the right root stock or it hasn't gotten proper care. Unlike peach trees, apple trees easily live to be at least 100 years old.
Your friend as 3 options: grafting cuttings onto new root stock, air-layering (I've never heard of it being done but why not?) and cuttings.
The cuttings should be 4 - 6 inch softwood (from this year's growth). Use a rooting hormone and plant them in half peat/ half perlite. Use bottom heat and a humidity dome.
BTW, fig trees and pomegranite trees both grow easily from cuttings.