A Tesla Model 3 battery is expected to last at least 400,000 miles with improvements that in 1~2 years could see 1 million miles realistic.
So a battery replacement after 400,000miles+ at $5~$7,000 is reasonable if the rest of the car wasn't uneconomical by then.
Is it an issue for most people? No, not seen many second hand cars that have racked up 400,000miles.