You should easily get 250k+ miles out of the battery pack, assuming that they are properly designed and build. Yes, there are examples like Nissan Leaf (no thermal management) and Chevy Bolt (they catch on fire for no apparent reason). Even Tesla had some batches where BMS would fail (not the battery, but BMS failure also makes battery unusable). But overall batteries are pretty reliable. Several Teslas have already made it past 500k miles mark.