When Microsoft announced Windows 10 S, it was immediately clear that this SKU didn’t fit well into Microsoft’s lineup in fact it was pitched as a complete product and that it could also be upgraded (for free) to a full version of Windows but based on documents I was able to view - Microsoft is changing the course with Redstone 4 to make the idea of S fit better into the company’s portfolio of Windows 10.
On the commercial side, Pro S is only available with Core, Value, Entry, and Small Tablet with Core+ and Workstations being left out of the offering.
Microsoft officially says that there will be AV/Security apps in S mode. Does this mean that traditional AV software from third-party companies will run in S mode - I don’t know. If MS would break their own promises it would be a big bummer because this would have an dramatically impact on the performance.