A dead battery isn't dead, it just has a reduced capacity. Usually the battery is considered dead at 80%, so it's a 400 mile truck then. That 400 mile truck is still useful, so it'd probably be cheaper to sell the 400 mile truck and buy a new truck then to replace the battery and sell the old battery.

Another question is: how much of the savings in fuel costs going to go to the operator and how much is going to go to Tesla in purchase price? 5 years ago it was announced at $180K, but it's certainly going to sell for a lot more than that. A Nikola Tre with 360 mile range goes for $270K, so it's quite possible that Tesla will charge $400K for theirs. So you might start off at about $250K in the hole so it'll be hundreds of thousands of miles before the Tesla is cheaper than a diesel.