I didn't realize that you could no longer easily go back to a previous version of Windows during the first 31 days (From Point 4 of the article). This will make me think twice before upgrading to Windows 10. Fortunately I keep my OS and Data on separate partitions, so the "Nuclear Option" of returning to Windows 7 is easier.
Just to clarify, I believe that's refering to the fact that you are now, (as of this date), more than 31 days past the end of the free upgrade period. Therefore, if you took them up on the free upgrade at this point you can no longer revert to a previous version because that option no longer exists.
However, if you upgrade now you will have 31 days from now to determine if you want to stay with Windows 10, if you don't then you can revert to the previous OS. But again, once the 31 days expires that option is removed.
I could be wrong, the info in that point is a bit ambiguous.
Just do a drive image backup before embarking upon the upgrade, then you can always replace Windows 10 with your current OS no matter if the 31 days has expired or not.