cupsd[873]: Printer drivers are deprecated and will stop working in a future version of CUPS. See https://github.com/OpenPrinting/cups/issues/103
You are (like so many other people) confusing IPP the protocol with IPP the driver, which is honestly not your fault and a terrible naming mistake.
And like you mentioned, people have way older printers because if all you do is print monochrome and mostly text, a printer from 2004 doesn’t lack much aside from AirPrint / Mopria. Which is why I suspect CUPS will not deprecate at least PPD drivers.
So yes, CUPS itself will only support IPP without any printer-specific driver. Since mobile phones also only directly support IPP this sounds like a reasonable decision.
Ah, yes. Thanks for pointing that out! I wonder how much more secure that will make things for those who have to use legacy printers.
> Since mobile phones also only directly support IPP
Technically AirPrint is not IPP Everywhere, they use a different raster format and some different glue. For example my Brother printer supports AirPrint but fails ~50% of the IPP Everywhere self-certification tests. But that’s splitting hairs.
> As for printer drivers, those few printers that "need" them can migrate to standalone applications/services using the CUPS API to provide an IPP Everywhere-compatible Printer instance. PAPPL provides a convenient framework for easily creating these applications and porting existing CUPS raster drivers, and the following printer applications are already available or (in the case of Gutenprint) under development:
[...]
> ps-printer-app: PAPPL-based PostScript printer application that supports all CUPS/PostScript printers via PPDs and includes all of the Foomatic and HPLIP drivers.
So drivers will still be supported in a sense, just not directly by the CUPS daemon.
They claim that modern printers implement IPP and that should be the preferred protocol for printing. In IPP, printers advertise capabilities and are able to handle different high-level printing requests.