Why? I can upgrade, that's not a problem. I'm just saying macOS works fine so far, almost all of the software works too. But I see increasing amount of announcements like this one suggesting that I'll have to replace hardware to get the latest versions. So I guess I will do that only to be able to use that software, not to get better performance.
You can install Linux on the hardware and get full x86_64 support again.
> I'll have to replace hardware to get the latest versions
Or switch software. Windows will run via Boot Camp and depending on your hardware Linux might work too.
Well Apple isn't making amd64 systems anymore, so software support will naturally start to waver.