The 2019 iMac came nine months after the Coffee Lake Macbook Pros of July 2018. Why that happened is becoming much more clear.
The starting point is the Apple Q2 2019 Financial Report. Apple CFO Luca Maestri, in his opening remarks, noted a slight reduction in Mac revenue “with the decline driven primarily by processor constraints on certain popular models.”
Whatever does that mean? How could Apple, which uses only a small percentage of all of Intel’s CPU production capacity, experience “processor constraints”?
Here’s what I now think.
The Drive to 10 Nanometers
Recall that Apple shipped (mobile version) Coffee Lake MacBook Pros in July, 2018 and upgraded its MacBook Air (Amber Lake, a mobile CPU) and Mac mini (Coffee Lake) in October 2018. But the iMac, it appears, was destined for a stronger CPU upgrade, notably the 10 nm process Canon Lake. To read more about Canon Lake, see “What to Know About the New Intel CPUs: Coffee Lake & Cannon Lake.”
But Intel has had problems achieving the Canon Lake 10 nm process mass production. It appears that Apple waited for Intel to resolve these issues as we drifted into late 2018, and then Apple was forced to delay the presumptive 2018 iMac into 2019.
Time Marched On
In early March, I suggested several reasons for the delay. “Why Apple May Have Delayed the New iMac.” Reasons number #2 and #3 now look like the best candidates.
 Or Apple had already committed to the follow-on CPU, Cannon Lake, and Intel continued to fumble Cannon Lake yet further, likely infuriating Apple. See: “Intel Cannon Lake release date, news, and rumors.”
 Finally, Apple may have planned all along to go with ARM in a major architecture shift, just as the company may be doing with the 2019 Mac Pro.
So what to do? Apple waited for Canon Lake, got frustrated, then settled for Coffee Lake and Coffee Lake Refresh (on the high end) with a March 19, 2019 release. TMO took a look at the Intel part numbers and discussed the CPUs used. “Details on Intel CPUs used in Apple’s 2019 iMacs [Chart]” At this point, why even bother with T2 chip integration previously planned. Time to ship product!
And so, no Canon Lake to be seen there.
An ARM and a Leg
At this point, with the move to A-series CPUs in the Mac line almost certain, we’ll likely never see a Canon Lake iMac. Or Mac Pro.
When Apple was dueling with Qualcomm, it turned to Intel for 5G modems. Apple wasn’t happy with Intel’s progress there. Combine that with the Canon Lake snafu, and Apple has probably had it with Intel’s fabrication efforts.
Going with its own A13 (and successors) in the Mac, which is a 7 nm process CPU, has all kinds of advantages. Of course, the obvious ones are control of a critical Mac component, superb integration with macOS, and, of course, better control over Mac release dates.
A myriad of other technical details (e.g., virtual machine hardware) will probably be revealed at WWDC 2019. As Tim Cook said in the latest financial results session with analysts, “You’re not going to want to miss this one.”