Even if it did wear out after 200 cycles, you could still use it as part of a hybrid battery pack. Imagine 50% lithium ion, 50% lithium sulphur. If LiS has 4x the energy capacity of LiIon, you'd have 2.5 times the maximum range of a pure LiIon pack. But most of the time, you don't drive anywhere near the full range, so you discharge the LiIon pack first, and only dischange the LiS pack on those rare days when you need the extra range (or if you only very very rarely need the extra range, dischange the LiS half occasionally to avoid the LiIon half wearing out first).