It is going to be fascinating to see whether several of the restrictions stated for hardware compatibility with Windows 11, for machines that are already running Windows 10, stick.
Just for amusement, I downloaded and ran the PC Health Check App (arrives as an MSI installer), and have been told that my machine doesn't meet the requirements. And that machine has an i7 processor (early, admittedly), 16 GB RAM, 1 TB SSD but no TPM. It's UEFI/BIOS "born on date" is 4/21/2014. While not exactly a youngster in the computer world, I've got machines much older than this one running Windows 10.
The potential exists for a lot of very upset Windows 10 users if they stick to their stated compatibility requirements for any machine to run Windows 11, not just those being built as we speak.
I won't mind sticking to Windows 10 provided it keeps having security patches applied.