They will have to support Windows 10 for longer than five years
Given that some PCs only a few years old won't be able to run Windows 11 due to the TPM 2.0 requirement.
And don't tell me about "oh there's a slot where you can insert the TPM" because the average consumer is not going to open their PC and install something. Even the ones that are firmware upgradeable won't help unless Windows 11 does it as part of installation procedure.
Otherwise there will be a billion vulnerable PCs in early 2027 with another 5-10 years of useful life.