Of course you could install the full version when Windows 11 published. You only need a Windows 11 RTM ISO image, which will be provided by Microsoft on download Windows 11 website, just like current download Windows 10 website.
Besides, if go back to the previous version doesn’t work but you want to go back to Windows 10, you could use media creation tool to download Windows 10 21H1 ISO, in-place degrade to Windows 10.
https://www.microsoft.com/en-us/software-download/windows10
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