They have been still selling Nano S this year, 2022. And, afaik, by the European laws (Ledger is French, right?), they have to offer full support for at least 2 more years.
So for now I would not be worried. Not yet. After 2024, that's another story.
Support doesn't mean they need to update firmware and individual coin apps, it only means they have to answer to people about complains and maybe replace device if they are in warranty.
I don't know if they are so stupid do make separate apps for each model, that would make their work much more complicated, but it's possible judging how they handled updates for previously retired models.
And I can't foresee a situation where the bitcoin app becomes so large it doesn't fit on the Nano S at all, at least, not until such a time in the future that most Nano S devices have experienced hardware failure. As I said above, there is no incentive for Ledger to forcibly phase out these devices.
Incentive for them would be to sell a lot more S plus and X devices, to all the people that couldn't use old model S anymore.
I never liked their model of having to update firmware with Bitcoin app in ledger live, even if you are not using that software, so they are forcing you to use it.
Trezor did much better job, they don't have any apps installation, so process of firmware updating is much faster.
That's why I consider SeedSigner a strong option. It's just a Raspberry Pi Zero (not too far from a general purpose computer after all, just cheaper) with a fancy enclosure and the necessary hardware and software added to it. It's cheaper too than the 200$ mark. Ah, and no WiFi, so less chances for errors.
I like SeedSigner, but it's not solution for dummies, and I think we have larger amount of dummies who are using hardware wallets.
SeedSigner are similar DIY devices are more intended for geeks, and people who like making things for themselves.
You don't have to trust in secure element (there is none) but you don't have to keep seed words on device also