One thing that I don't understand, does the Ledger company sell the Nano S in batch so they update their hardware with the new coins.
Or they release a new update for the hardware like a firmware where the users should manually update the Nano S in order to get working with the new coins that have been added?
There's firmware updates like the one needed for BCH support.
You didn't need to buy a new Nano S once they added BCH, you simply made sure you're on the right firmware version and installed the BCH app.
Same goes for newly added altcoins, since the chips are the exactly same in every batch.
It's all pretty straight-forward once you have a Nano S in hand and get to try it yourself.