> As cheap as the mass produced ones with the economies of scale?

Of course not. This has _never_ been the case. You get spare parts from manufacturers initially, usually at a higher price (buying new bikes and parting them has been a thing for decades). When manufacturers stop producing spare parts, you can cannibalize existing cars that are taken off the road for other reasons (crashes, severe cosmetic damage, etc.).

This is enough to last you at least 2 decades. And after that time, maintaining a car makes sense only for sentimental reasons. If there's demand, there'll be supply. There are companies that are _still_ making new parts for Trabants!

> You're talking about a car ECU. Go see how much ECUs cost that don't deal with power electronics.

You don't have any idea what you're talking about, do you? ECUs on EVs do NOT deal with high voltage directly. They are just regular computers that run off 12V and output control signals over CAN lines, just like on regular gas cars.

The drivetrain on EVs is now integrated, with the power inverter sitting next to the motor to minimize transmission losses. It usually exposes a simple CAN-based control interface with a bunch of diagnostic data and YUGE high-voltage power leads.

As a result, you can buy EV conversion kits that reuse Tesla motors and power electronics. E.g.: https://kaizenmotoring.com/complete-tesla-swap-guide/

If anything, EVs will make it easier to repair stuff once the technology slows down a bit.