Lithium ion batteries are totally different than lead acid 12v batteries. Most manufacturers warranty the pack for 8 years+ so you can be pretty confident it will last well longer than that, as they really don't want to be replacing many of them. Most EVs have sophisticated battery management systems with active heating and cooling to baby the battery pack to maximize its life.One of my problems is that I only use my car for short distances about once a week. A 12volt battery usually does me about 2 years, so I was wondering how the EV's would accept those sort of conditions. I think the last thing anyone would want is to replace the big battery in an EV. No doubt I would still have to replace the EV's 12 volt battery fairly often.
I think you can get a used Nissan Leaf for $10kish. That would be suitable for driving <100km once per week.
It will take a long time for Teslas like Model 3/Y to become common enough to be reasonable used cars. Their resale values are crazy.