I saw that notice on mom's computer and I uploaded Windows 10 on her computer. It worked great but she had problems with passwords. I had backed up all her data, so that was safe. But her Windows 10 upgrade did not remove her data. When turned on for the first time her data was still there.
On my laptop I clean re install a lot so I do not know that it will work out when Windows 10 arrives for my computer.
I checked and Windows 10 has a Factory Rebuild in it. I just have to get the SN# off the one they install then I go to the Microsoft Website and ask for the rebuild. I am not sure if that is correct but I think I read that right.
I do clean re installs all the time to keep my computer clear of of Nasty Trash I may download from time to time.