Soldato
Now, I dont know how the price of used EV's is going to hold up but I would guess that they will hold up quite well and only drop in price once they become unusable. This is quite different to the depreciation model for ICE vehicles where old and cheap options will still retain new levels of performance.
And as a mechanic, you understand how value can be retained in older cars by repairing them with parts from other cars, that have been scrapped and written off.
As more and more EV's come to market they will be more that are in accidents etc. which means more spare parts, so those 'unusable' cars can be made usable with spare parts.
You only need to look at the cost of a Nissan Leaf 24kWh battery pack, they sell for a pretty penny even when depleted below 70% as they can be recycled into stationary storage projects, and ones that still have good capacity can be used to make a car that might be 8 years old like new again, as you put it.
If you are of an age to still be working when EV's become the main new cars being sold are you going to learn to repair/service/sustain them?