Admittedly my use of the term "Apple-designed" wasn't specific enough and your "by some measure" observation is correct. Maybe "Apple-optimised" or "Apple-specific" would have been better terms to have used. I'm assuming here that the Intel design team while still employed by Intel was designing one or more generic modem chips rather than doing custom silicon specifically for Apple but someone please correct me if I'm wrong on that.By some measure, iPhones already have 'Apple-designed' modems in that they have Intel-designed modems and Apple is in the process of buying Intel's modem division. If Apple wanted to stick with 4G modems until its own 5G modems were ready, it wouldn't have needed that multi-year agreement with Qualcomm.
If my understanding above is correct then once those Intel engineers are Apple employees I assume they will not in any way be expected to create modems for the general phone market but will only be tasked with creating the most streamlined and efficient modems they can specifically for use in Apple products. At that point I really do wonder what fat can be cut out, what co-packaging or even wafer-level integration with other iPhone/iPad/etc circuitry might be possible, and what patented Apple technology used for power optimisation on the A-series SoCs might be able to be carried across to the modems.
I do hope this acquisition and building the modem design team is more than just getting design control of another piece of the iPhone/etc internals purely for business reasons and that it will also lead to genuine design optimisations that make the iPhone product better and/or more efficient than they would otherwise have been if they still used third-party components not as single-mindedly designed specifically for Apple's products.