A change of this magnitude would be announced well ahead of time. No way Apple is going to cut Intel machines cold turkey with no notice. There are too many Intel machines still out in the wild. This isn't the PowerPC days.
High Sierra 10.13.4 started warning that 32-bit applications would no longer be supported in future versions of MacOS, and Mojave 10.14 still supported 32-bit apps.
People that are not Apple enthusiasts do not upgrade their machines every year. Lots of people don't know or care what OS they have because most of what they do is done in the browser. The oldest Intel machine is only 5 years old. Until more Intel machines are retired, the lack of an Intel OS will create large OS fragmentation, with Intel machines on Sequoia and Silicon machines on 16+.
iOS 15 is old but just got a security about a month ago, and the majority of apps are still written for iOS 15 baseline requirement. Only the nichest of apps require iOS 16+. For apps that no longer get updates on iOS 15, the "last compatible version" from the App Store works fine. And yes, there are still apps in the App Store that only require a minimum of iOS 12 (Roblox), iOS 13 (Zoom), iOS 14 (Snapchat). To a lesser degree, I see apps that only require iOS 9, like VLC Media Player.
Windows 10 remains the #1 Windows OS, because Microsoft was too aggressive and dropped support for machines that were little over 4 years old when Windows 11 was released.