We do not know the quid pro quo that led Apple to use Intel's modem. My *guess*, and I stress that it's only a guess, is that the real story here is that what Apple got in return was some level of access to Intel's base band cells, and thus the ability at some future point to integrate those onto the A# chip.
Of course this isn't really progress (except insofar as it makes the phone slightly smaller and cheaper to manufacture) unless that base band gets improved, so I'm assuming the relationship is not purely a licensing of the cells, but permission to use them as a starting point to modify them in whatever way Apple desires.
The question, then, is whether Apple can do as good a job as QC once they have this control.
On the positive side, you could argue that they've managed to to pretty well with the CPU, the GPU, the ISP, the motion sensor coprocessor, etc; and they appear to be willing to pay the higher costs (in process, in area) to embody the best feasible algorithms on their chips. Which would suggest that they can attract top base-band engineers, and can tell them to go more-or-less wild in implementing state of-the-art in Apple silicon.
On the negative side, the first question is: how long does this take? Two years (so we see the esults in the A12) is maybe OK. Five years of sub-optimal modems before we get the good stuff is problematic...
The second question is how much of the good stuff is Qualcomm IP protected? And because it's not ESSENTIAL implementation, just best implementation, it isn't subject to FRAND licensing.
The third, related, question, is how much of the good stuff is only known within QC --- it's not patented, it's not published, it's just trade secrets learned from so many years of being in this business?
I guess we're going to see over the next few years...
(It is also important, I think, to distinguish between "measurable different performance" and "not good enough performance". There's obviously a certain crowd that take it as a personal insult if their equipment is not state of the art along whatever dimension they're chosen to prioritize; but that's a small fraction of the buying public. What matters in the real world is the extent to which this inferior modem results in a clearly inferior experience. Given how uneven the cellular experience is anyway, under normal conditions, it's going to be very rare that people (even people both on the same carrier, but one of them just happens to have the Intel modem and the other has the QC modem) are going to be doing something so identical that they will really experience the difference.
I suspect, at the end of the day, this will be a re-run of the TSMC vs Samsung A9's. Interesting to a tiny group of people who really care about fab details; supposedly the most important thing in the world to a small group of fanatics bent on proving how their team is superior to the other team; and UTTERLY irrelevant to the wider world, to Apple's sales, and to the normal iPhone experience.)
