Batteries tend to be at 80%+ capacity after 10+ years. You still see EV1s on the road with original batteries - and those batteries are ancient tech compared to modern batteries. The lack of moving parts means EVs rarely need service of any kind. There are no fluids, no pneumatic system, no gearing, or other Rube Goldberg machine things in it. It’s just copper and magnets, powered by maxwells equations rather than dinosaur juice and fire.

The issue with EVs is charging infrastructure. However that will continue to improve over the next 10 years. As will the economics - there’s no reason for an EV to cost so much. They’re just premium priced because everyone wants a Tesla margin, and they’re used to demanding high prices for their complex mechanical gear and belts beasts because that complexity of machine really costs that much. BYD is proving tho you can deliver a quality $10k EV at much lower costs than we see coming from the major car makers.

I’d note your $500 replacement is if you do it yourself with a scrap engine. You can’t take it to the dealer or a shop and get a major change to the car done. So while that may be your economics, it’s not a very widely shared option.