What happens the older chips? Do they just keeping delivering services to a lesser AWS tier, or do they get junked? I'm not much into cloud stuff and didn't even realize Amazon made its own silicon these days.
Now, I manage many servers at my job that are much older than that, but only because the operations budget and the capital expenditures budget do not take this into account.
Customers will want to migrate anyway because the newest types offer much better performance and pricing. At which point AWS may decide there's no demand for new instances of that type and just remove it from the API.
Selling them? Running other services on them? Just keeping them in reserve? Or all turned into e-waste?