FWIW I upgraded to windows 10 on my bootcamp partition 100% through vmware fusion using the official win10 iso. I got the same error you linked until the lates

FWIW I upgraded to windows 10 on my bootcamp partition 100% through vmware fusion using the official win10 iso. I got the same error you linked until the latest rollup fix (which put my install into a boot loop due to nvidia geforce creating a phantom user but that's a whole different problem). Once I installed the rollup it gave a different error and then took a day or two for the activation servers to finally work and activate the install. I only run windows natively to play games so it only runs for 2-3 hours at a time. It took until yesterday to get it all sorted out. I installed win10 within a few hours of the iso going up.