By the time your traction batteries are 'dead', the rest of the truck should be near the end of its service life (150,000+ miles).

So far upgrading batteries isn't plug n' play, the retrofit/upgrade kits we have now ($30,000+) also involve changing electronics. Who knows, maybe there will be DIY upgrades in the future. I can't imagine strong demand to keep high mileage Escape hybrids on the road. The CVTs will be expensive to replace since they aren't a Ford part.