Tesla guarantee their EV batteries for 8 years and re-cycle batteries into their domestic "Power Walls".
There are enough early Tesla Model S vehicles in North America with 200+k miles and 10 years use with batteries that don't yet meet the Tesma definition of "not fit for use" to suggest battery life will be no more of an issue than ICE Engine life.
I don't think EV depreciation will differ from ICE car depreciation.
Watching Jonny Smith on the Late Brake Show and he was opining that one reason that used EV values are holding up so well is that batteries are lasting far longer than anyone predicted. AIUI the end of life criteria for EV batteries is around 75-80% of original capacity. and even then there's plenty of life left in them for grid storage uses.
My LG wall battery is guaranteed to still have 90% capacity after 15 years, and it's basically the same tech as EVs, so I reckon it's going to be entirely feasible to see EVs running around for 20-25 years or more. If our Mini drops to even 50% after 15 years it will still have a range of 50 to 70 miles which would be more than enough for me to tootle into town for the groceries.
There's also the huge demand at the moment, of course, but even in future years once initial demand has died down one can expect the value of used EVs to outstrip ICE vehicles, not only from the longevity and cost of ownership, but also from the spiralling cost and lack of availability of petrol and diesel.
