The used car market exists.

EV car batteries last at least 7 years, in theory and in the 2010 cars still on the road. After 7 years, they need a battery replacement (similar to how an ICE car needs engine work, just a one-shot replacement instead of lots of minor maintenance and repairs), and the old batteries are easily refurbished into other kinds of batteries (like home backup batteries) where charge-per-unit-weight-and-volume is less critical than in a car.

The average car in the US is said to be older than 7 years, and ICE powered cars do not normally need a new engine at that point. Cars are usually scrapped at 14 years or more, I believe.

Anecdotally, a valve cover gasket, oil pan gasket, brake discs are going to be recommended on many cars after 7 years.

There is already datab out there from high class rental companies that reduced maintenance from oil changes, brakes, and major repairs easily leaves room for new batteries.

Valve cover or oil pan gaskets are replaced when needed, not because some time has passed. Besides that they are a minor job both in cost and invasiveness compared to replacing a battery pack, this is very much comparing apples to oranges.

Typically ICE cars do not require engine work at 7 years of age.

I held my previous car for ~ ten years (Subaru WRX) and intended to hold the Model S that replaced it for 15. Alas, when the option of all-wheel (dual motor) became available I did sell it to a friend and upgraded. Based on the data from the Tesla Roadsters, they hold up fairly well after years (mechanically impeccable due to few moving parts). Early data from the now ~ 7 year old Model S suggests that it's even better. I known nothing about non-Teslas, but IMhO, Tesla sets the standard that all EVs should aspire to.