I like everything you share there... but still struggling imagining them putting on one of their campus productions mostly to show a single Mac or Mac + single iPad. And if they do, suddenly there would be all this angst over a single Mac having M3 and all others on M2... including the ones that sell the highest volume for them... creating the scenario of "wait for M3 versions in a few months" that much harder.
The need for a 'dog and pony' show is completely not necessary.
Tell folks to go to apple.com/watch_the_video and play video and read the press release. Done. All the more so, if the outside is basically the same and primarily just an updated logic board with a new M3 on it. (maybe some small tweaks to the screen and/or camera. )
If the iMac has a M3 exclusive for 3-4 months and it can't generate a big sales generating 'buzz' just on that ... then the M3 has major problems. Shouldn't need a 'show' ( ooooh the new iMac is better than sex . It leaps tall buildings in a single bound ... blah blah ). Send out 50 loaners for review after the 'overview' and the market 'buzz' properties should just take care of itself. Jumping two generations so it should crush the intel models and put a big gap with the M1 on a number of fronts. Sell by 'doing' as oppose to reality distortion field 'talking'.
iPad Air with a M2 ... essentially the same thing. No dog and pony show necessary. ( no multiple generation leap though. More affordable than an iPad Pro is the main message. )
Last Q4 Apple didn't have new MBP to sell . They defacto cut prices to move product. Can do the same thing here for the M2 MBA/MBP 13"/Mini product this year. (Mini a bit less so since it is a bit 'younger' ) At the same time build M3 inventory so that can do a high volume launch in Q1 2024 for those. There are several things Apple can do to reduce the 'Osborne effect'. But the fact the M2 models are already over a year old, there is likely some volume drop off anyway. Most of the folks who wanted a M2 MBA bought one. The ones waiting on M3 will likely wait. ( what going to go off and buy AMD/Intel Windows instead? Probably not. ). the iMac is about as non-substitutable a good (for a laptop) as it can be and still be a Mac.
If the A17 in the iPhone 15 Pro models sells well then N3B wafers are throw at that. If it is a volume product pissing contest the Pro models wipe the floor with what ever Mac model you want to throw out there. if the A17 SoCs largely undersell .... well TSMC N3B is so slow/hard to make, Apple can't really respond. ( It takes longer than a quarter to make either one M3 or A17 .. so by the time know want to switch allocation it is already
way too late to do anything that quarter. ) . Coming up 'short' in A17 unit availability is way , way , way worse than having too many M3's. ( if the iMac M3 sold 'short' there are about 5 other products it can get tossed into relatively quickly. ( MBA 13"/ (maybe 15") , MBP 13" , Mini , iPad Pro 11/12" ).
The primary 'hand me down' location for the A17 is the plain iPhone 16 which isn't coming until September 2024! Because it is on a fixed-in-stone dogma of every September.
Going heavy on A17 allocation means they can turn it off if has too much and then can just do that much more M3 earlier in 4 months than they thought they could. Meanwhile, they build up M3 inventory because iMac probably is not soaking up all of them. If the iMac miraculously oversells ... that is just more money sooner for Apple . Not really a huge 'problem' to have more money quicker. ( Apple can slide the Mini consumption of M3 back a bit in 2024. )
Your objective seems to be highly focused on just winning the Mac units sales spiking contest the first quarter the M3 is released as opposed the lifecycle.
On the flip side, Apple wants to maximize revenue and there is a rhythm of Phone in Sept and Macs in Oct. It's hard to picture them skipping an October event altogether or doing it with a press release. So I think we need some shifts in the rumors (by paid analysts) to bring on some other Macs to join this lone iMac hypothesis for M3.
If the economy slows down because consumers are getting slightly more cautious with their spending, then more affordable Macs would go a long way to keeping the year-over-year Q4 numbers looking OK. Last Q4 Apple didn't have anything new. Nothing. So even incrementally more iMac sales on top of 'flat' year-over-year for rest of the line up has decent chance of doing just fine. [ It isn't like the general PC market is going to so gang-buster, break out numbers Q4 . There overall sector is drifting so Mac's coasting for a Quarter isn't going to make much of a difference one way or the other. ]
P.S. The sibling rivalry thing is not a necessary thing either. Well the iPhone got a 'dog and pony' show ... the Macs should get one too. Sometimes. New Macs may or may not be ready in October . If not they it is quite alright to skip October. The fixed-in-stone iPhone thing is dual edged. It has lots of downsides also. The leading edge iPhone happens to make enough money to cover the negative aspects up. But it too is starting to wear 'thin' on this contrived date that has no technical requirment/merit in it at all.
There is broad enough number of Macs to ship that Apple should just spread them out and ship new stuff when it is fully ready to go. Shouldn't be waiting on specific fixed dates in time every year. ( if distribute the Macs over the year ... should regularly get something popping out in Q4 of the calendar year. )