Hmm, in theory it’s not going to be an issue for the vast majority of casual users and actual IT professionals will know what they’re doing. Switching it on, that is, I still think the number of people with incompatible hardware that are not ready to upgrade yet will be.
The hardware that’s out there is going to be an issue; MS going to have to continue supporting Windows 10 for a long time. For reference… the NHS is only just managing to drag the last few heaving old machines over from Internet Explorer to Edge/Chrome

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Hell as recently as 5 or 6 years ago the bookies was still on Windows XP - by that time totally unsupported- until it was discovered that they were WIDE open to hackers and finally made the jump to Windows 10.
To further compound issues… there’s a global shortage of the components needed to make new chips. If everyone suddenly is desperate to get their hands on a newer laptop or mobo/cpu for their desktop, it’s going to be Graphics cards/PS5 all over again. Manufacturers will fall way behind demand and tech will fall into a scalpers black hole.