I wouldn’t call it a “discovery” of mine, just my interpretation of the rumour mill. See the “The First Arm-Based Mac?” heading near the bottom of the page:
Quick edit: it’s seeming like the next 27" iMac will be Intel, while the next 24" iMac will be Apple Silicon. My point is that the next one to come out seems like it’ll be the Intel-based 27", not the 24" Apple Silicon. Again, all speculation!
Over the next nine months I suspect we’re going to get one last refresh of Intel Mac hardware (possibly every line except the mini, but not every model in every line), and everything else for years to come will run on Mac processors, supplemented in a few machines with AMD GPUs.
I’m potentially in the market for an AS-based iMac (whether Pro or not). I guess that will appear later rather than sooner. Which would bias me towards an (also unannounced) AS-based Mini with a nice screen.
As for a 24-inch iMac, that size only makes sense if it’s a replacement for the 21-inch iMac, in which case there should be a new 30-inch iMac to take the place of the current 27-inch models. Going from 27 to 24 inches would be a huge downgrade in display size. It makes no sense at all that this would be the only iMac Apple would make, and makes almost no sense that it would be the first iMac they’d release with Apple silicon.
When Apple started its transition to Intel, its first two releases were an iMac and a MacBook Pro. Repeating this release, for the same reasons that were valid in 2006, makes sense. Notebooks have long been the most popular types of Macs sold, so the MBP will be the unit most will buy, and the notebook will better show off its speed and battery life comparisons with Intel models.
Apple will probably make tentative steps if they don’t have a separate desktop processor available immediately. And for the first desktop unit they don’t want to start off with the relatively clunky Mac Mini (clunky in that users need to procure keyboard, pointing device and monitor, so it makes sense that they start with a lower-end iMac, and fill out the roster later. (We’re going to see the switchover really fast, just like last time.)