If market saturation and exposure is king then windows 10 has won BIG TIME. Supporting one platform will make MS billions (like gutting their QA dept.), i'm sure they cannot wait for Windows 7-8.1 to be obsolete so they can focus on making/supporting windows 10 builds.
My personal experience, I don't like having to administrate windows 10, seems like MS really doesn't want you to have control over their OS, rather the other way around. Which is fine for consumers, not so much for enterprise.
The amount of telemetry built in to ALL builds of windows 10 is sickening and lord only knows what MS is truly doing with that information...
But with a lot of their services going cloud/azure based, it doesn't leave much for other sectors (education, healthcare, finance) to keep things in-house, giving that much more control and therefore money to MS.
From a purely financial standpoint, windows 10 will be a HUGE success for MSFT. It can be an absolute nightmare to support though.