I ran the Windows 11 Health Check app (link in Joe's CNET post) on my wife's Thinkpad L430, a 'business' laptop which I though would run Win 11. It is perhaps 8 years old and has a 64-bit processor. (I recently put an SSD in it.)

The Health Check app said no, but didn't say why not. I suspected the reason is that Win 11 requires a TPM (Trusted Platform Module) version 2. I followed the procedure HERE to check that and discovered that the laptop has version 1.2

TPM v2 was released in 2014 but laptops with v1.2 may have been sold after that date.

So it looks like Windows 10 really will be the last version for many machines ;)