There are ways around that (open core patcher).
Right now, AFAIK, every OS since the Apple Silicon Macs first dropped has continued to support AS going all the way back to the first M1 CPUs.
OCLP is used on Intel systems to allow installation of a newer OS than Apple supports. Depending on the specific system and OS version, it can work perfectly or it can have a mile long list of annoyances/quirks/things that just don't work.
The day is coming when new OSs no longer support Intel Macs. When is that happening? It's hard to read Apple's mind, but the PowerPC transition might be a guide.
The last PowerPC Macs shipped with OS X Tiger, 10.4. The first Intel Mac shipped in early 2006, and the transition was considered "complete" with the Mac Pro shipping in August 2006. The last version of OS X that supported PowerPC Macs was OS X Leopard, 10.5, which shipped in 2007.
It was a bit of a different time, though, as Apple was on roughly a two year OS release cycle then and not an annual release cycle as they are now. OS X Snow Leopard, 10.6, which was the first to NOT support PowerPC, was released in 2009, or 3 years after the last PowerPC Mac shipped.
The AS transition hasn't been quite as quick or smooth, a lot likely to do with major global events outside Apple's control. The first AS Mac shipped in early 2020, but new Intel Macs were still shipping until mid-2023 when an AS Mac Pro was finally released. The first M1 series Macs were very much "bridge" machines, so much so that Apple actually retained the 16" Intel MBP and the high end 13" Intel MBP well into 2021. Even after the first AS machines shipped, new Intel models like the 2020 iMac 5K were introduced.
I think realistically, at a minimum, the macOS version released in 2026 will PROBABLY support Intel Macs, although I'd also not be shocked if 2025 ends up being the cut-off. If anything beyond there continues supporting them, it will be a bonus.
Once Apple drops support for the architecture, I seriously doubt that OCLP or anyone else will be able to make it work. It's not impossible-as an example, Apple left a lot of PPC code through 10.6, and there's been some success patching together early betas to boot on PPC. That's very much a hobbiest project, though, and realistically it's still happening over a decade after the OS's release and without any software that benefits from the newer OS.