According to people who are usually in know regarding things like this, Windows 8 will feature multiple SKUs. You can think of SKUs as versions; each SKU will feature a different version of the code that is Windows 8. Similarly to how we currently have Windows 7 Starter, Home Basic, Home Premium, Professional, and Ultimate, we can expect to have all of the above in Windows 8.
Of course there will be a SKU for ARM as well. Windows 8 is pretty lightweight, so there really isn't a reason to feature more versions than just a Consumer and Professional version. It's clear that Microsoft doesn't particularly care about consumer confusion. Windows 8 is pretty revolutionary, but it would appear that Microsoft hasn't left some things in the past.