iPad Air 3 - Not sure many people were buying the Air 3 to begin with. For school or home, consumers bought the $329 model. For work, people bought the iPad Pro. The Air 3 was stuck in the middle like iPhone 8 Plus.
iPhone X and XR - Apple continues to sell previous iPhone models. You can't buy the 2019 MacBook Air. I don't think anyone expects Apple to sell the Intel-based MacBook Pro 13" along the Apple Silicon model.
Evidently it gets enough sales to warrant an extensively redesigned replacement though? I'm not sure how exactly their sales modelling goes with this but I feel like a lot of Air 3 customers might be redirected to the iPad 8, while the Air 4 gets a big chunk of its customer base from those who might have gone for the 11" Pro (one reason I wonder if the 11" Pro will either be phased out, or shifted significantly up in price and feature set, and maybe slightly in size).
With the iPhone X and XR even if they are selling previous iPhones, the point was Apple will lose sales of those with people waiting for the new model, just as announcing an Arm iMac now would hit sales of the Intel equivalent for a month or so. If anything I would have thought they would be more cautious with the iPhone as it's much more important than the Mac, and in particular we know Mac desktop sales are under 20% of total Mac sales so losing a few 21.5" iMac sales probably wouldn't be all that big a deal. The 13.3" MacBook Pro, and particularly the Air might be a little more disruptive, as those are probably the top two selling Macs.
In a another thread I mentioned that January is a good month to market new technology because that is when CES normally happens and wall street is anxious to see where the tech industry is going. So if you want media coverage before Christmas you won't have as much attention by consumers. CES is essentially cancelled except for some online meetings.
In this instance I was thinking for the broader consumer, who might not read too much tech news, but would probably see about an iPhone announcement (which gets a mention in the broader media each year) and anything that goes along with it. Currently I'm still taking Tim Cook's goal of launch by the end of 2020 at face value as we haven't heard otherwise from anyone else, though if someone like Ming Chi Kuo popped up and said manufacturing delays have pushed the launches back into next year I'd adjust my expectations accordingly.
Interestingly I'm still seeing late October shipping for the two models Kuo implicated to launch first (two port 13" MacBook Pro and 21.5" iMac) all other models seem to be in stock or have much shorter delays. Again, I don't necessarily want to jump on that as proof positive, but I do think it's worth bearing in mind when considering if an announcement on 13th October is likely.
I am sure the iPad Air (2020) is winning over customers who were looking at the iPad Pro 11 (2020) for Pencil 2 support and the edge-to-edge screen, but the iPad Pro 11 (2020) still has things to offer over the iPad Air (2020) like a better camera setup, LIDAR support, a better display (120Hz ProMotion) and the A12Z should still beat an A14 on multicore and (especially) graphics tasks.
Of course, Apple and TSMC will likely have the A14X ready by early 2021 to bring "order to the force" in terms of the next iPad Pro upgrades (with the 12.9" getting MiniLED, as well).
Yes, as above I think the 11" Pro certainly would be on the radar for consumers, and therefore might lose the biggest chunk of sales to the Air 4 until the next generation brings significant new features. Pros who actually want the extra features might be a surprisingly small cohort of customers for this model - I can imagine digital artists and anyone who wants a laptop replacement device will tend towards the 13" model, with price of little consideration. The 11" being well below the $1,000 psychological barrier probably appeals to just consumer iPad buyers a bit more, though.
