If the genuine nano will no longer be available, then large manufacturers like Adafruit will see the nano market shrinking, because of low apetence of the users to mount items that appear to be to old or more advanced items being avaialble.
Something like the resolution in photography: 6 MPx is more than enough for a decent print. But who will buy a 6 MPx photocamera?
Nano is a genial component. I am not talking about electronics (I am not the one to judge from this point of view) but about flexibility and easy of use. It has everything a beginner may wish. It is absolutely perfect for the educational purposes.
Nano is limited to what is needed and cheap enough not to cry when starts communicated MSS Protocol. Mountable on breadboard or perf. Whatever power source will fit.
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To be honest, I am afraid that the Arduino team will improve it to the point all these qualities will fade. They may enhance electronics so making it more difficult to use, more expensive because of useless capacities and so on.
There is a saying: "Do not improve what is good enough!" 