Microsoft could kill Linux's foothold in the server + SMB space right now just by simplifying licensing.

Get rid of CAL's. Charge a fixed price for a certain # of simultaneously running Windows instances, no matter how you run it. Even charging an ongoing subscription for this would be acceptable. Simplify the licensing situation for SMBs wanting to run an on-premise redundant systems, without needing diagrams to explain the difference between running, standby, CAL's, virtualization, etc.

If you're developing software for a platform, trying to figure out how to optimally license that platform should be the least of your concerns, so you can focus on your product.