Apple has an extremely competent team of chip designer, decades of experience in manufacturing and plenty of money to snatch top talents. If they want to be serious about modem design and it seems they want to, they will most likely succeed.
I'm not sure I follow you here. You seemed to be implying that after witnessing Blackberry failure to properly make their own modem you found the idea of Apple doing it laughable.
I was pointing to you that :
1. Contrary to Blackberry when they started trying Apple has been designing chips (CPU) for some time and has knowledge internally about how to conduct this kind of projects and how to build a team for it ;
2. Apple already understands and masters the manufacturing part of chip making ;
3. Apple is so rich and has such a brand that they can most likely buy the people mastering the knowledge they still lack (anything modem specific) from their competitors.
The idea that Blackberry was doing before everyone else seems to only make my points stronger. Apple will have less R&D and engineers training to do.
I'm not arguing it, I'm just saying it's a fool's errand.
If you build your own chip, you have to build your own mobile stack, and then maintain it and enhance it with the newer technologies, so it becomes a mountain of technical debt while your competitors can take what Qualcomm gives them and roll out a phone.
This assumes that Apple will maintain it's location as the top of the phone line and won't get eaten by someone else, if they slip, that mobile stack becomes a liability.
None of these advantages invent you a novel radio technology that is competitive with 5G yet unencumbered by existing patents. Designing a modem to spec is the easy part.
As a former person who was aware of Blackberry Mobility's Modem Firmware division by working within it.... LOL!