Re: A thought.
"For desktop and workstation, Microsoft will also, it seems, be charging based on the number of cores and/or CPUs basis. The 4 core (not CPU) will be the base price desktop OS, while systems with more cores (or more than 1 CPU) will have to pay more for the workstation licence."
No, Microsoft are not charging by # cores for Windows 10. Only by CPU type.
What they have suggested is that you will need the Workstation Pro license for systems with Intel Xeon or AMD Opteron CPUs. These are server / workstation class CPUs so it makes sense.