I'm not sure I can spot a dedicated memory chip anywhere on there. The very small storage space indeed hints at them just using the STM's internal memory. If that's the case, there's no experiments regarding 'extending storage' possible.
I came to the same conclusion, but they have new plan to make more money with their new hybrid s+ wallet with they just announced few days ago.
It is possible that the production will stop at one point in the future. The new Nano S Plus seems like a bigger competitor to the Nano X than to the old Nano S though. Bigger screen, better secure element, more internal memory, but no crap like Bluetooth or faulty internal battery. Maybe they are giving up on both the Nano S and X.
I am 99% sure that production os ledger nano s will stop in 2022, and they will blame short supply of chips and small memory for that.
People should think about and transfer their seed words to new device in time, or they will lend up like with ledger blue collectible.
I don't think that ledger will use better secure element, and screen will probably be same like for model nano x.