Oh man, an A12Z!! Gracious. I'm hoping you wind up pleasantly surprised by what Apple rolls out instead of me being cripplingly disappointed.
IMO, Apple will want to update the iPad Pro 1H 2022 with a new 4+4-and-8 SoC anyway. So why not use one they develop for the Air in 2021? Hell, I don't even think you need an optional pin out for the Air's SoC. If the Galaxy 20 can layer on up to 12GB of LPDDR5, I'm sure this theoretical A14X could do the same.
And this is appropriate for the price. The iPad 11 and 12 start at $800 and $1,000 respectively; the Air starts at $1,000. The two core iPad you brought up starts at $400.
Now, I don't disagree that an A14 would be viable. It won't get slaughtered by Tiger Lake, but it won't be a triumphant success story either. And if AMD is shipping a Renoir U successor in any kind of volume, well, good night.
Why take the risk when you could be dominating the headlines with stories of how your A14X takes the competition to the cleaners? Isn't that what you want every headline for your new machines to say, every year, forever and ever, just like the iPhone? That's easily achievable, and it's good business to be the best.
You'd still be bringing home a hefty margin on a $1,000 machine. It's not like your A14X is costing more per part than Intel wanted, and you're perfectly primed to reuse your 4+4 SoC in two other products the following year.
It was mentioned earlier in the thread but the iPad Pro starts with 128 GB (and will likely have the same 128 GB in the next iteration), and does not include a keyboard or trackpad. That Magic Keyboard costs $300-350. Also, the $800 model is only 11". The more comparable size is the 12.9" model.
The MacBook Air comes with not only an integrated keyboard and trackpad, it also comes with 256 GB storage, and the latest model even includes a True Tone screen and 2 Thunderbolt ports. And if you upgrade to quad-core, you also get 512 GB storage. So:
MacBook Air dual-core i3
256 GB storage
Retina screen with True Tone
8 GB RAM
Magic Keyboard with Force Touch trackpad
Touch ID
Two Thunderbolt 3 ports
US$999
MacBook Air quad-core i5
512 GB storage
Retina screen with True Tone
8 GB RAM
Magic Keyboard with Force Touch trackpad
Touch ID
Two Thunderbolt 3 ports
US$1299
iPad Pro 12.9"
256 GB storage
Retina screen with True Tone and touch support
6 GB RAM
Magic Keyboard with trackpad (not Force Touch)
Face ID
One USB-C 3 port and one charging port (in Magic Trackpad)
$1448
iPad Pro 12.9"
512 GB storage
Retina screen with True Tone and touch support
6 GB RAM
Magic Keyboard with trackpad (not Force Touch)
Face ID
One USB-C 3 port and one charging port (in Magic Trackpad)
$1648
IOW, to get a similarly configured iPad Pro, it costs $349 to $449 more than the MacBook Air. At entry level, that $449 represents a whopping 45% increase in price.
And ironically, the iPad Pro 12.9" with Magic Keyboard actually weighs more than the MacBook Air.
I suppose yet another possibility is Apple could sell a base model MacBook Air with A12 or A14, but the upgraded MacBook Air model with 512 GB storage would have A12X/Z or A14X.
I personally wouldn't want either though. I'm too spoiled by my 12" MacBook and don't want anything bigger.