Despite some concerns to the contrary, those who upgrade a Surface Laptop to Windows 10 Pro will indeed be able to return to Windows 10 S, as I knew to be the case. All you need is the downloadable recovery image.
Which is now available from the Surface website. But even without this image, if you make a recovery drive before upgrading to Windows 10 Pro, that will of course work as well.
Concerns about losing Windows 10 S after the Windows 10 Pro upgrade arose after a Microsoft FAQ described this upgrade as “one-way.” But this comment was misunderstood. What Microsoft really meant was that there was no way to do an in-place “downgrade” from Pro to S. Obviously, you can always recover to the original OS.
And now you have yet another way to do so. No worries, folks. This was always going to work.
And yes, this will work for any Windows 10 S-based PC.