My suspicion is the migration away from Windows will mostly be driven by W10 stupidities and EOL of W7. W10 is being excessively irritating and the Slurp is pouring gasoline on the fire. Most probably will sit on the sidelines until they absolutely need to replace W7. The migration of the technically literate away from Windows sets up a situation in 2 or 3 years were they are recommending migration to X. The literate would already have some experience with X and can give very good support from first hand knowledge.
Many have suggested Linux Mint as a good alternative, which it is. As many who not used a Linux distro before gain comfort with a Linux distro they will be more confident in recommending any distro to their family and friends. I am hardcore Linux only for my kit - Arch/Antergos/Manjaro. A couple of family members dual boot between Linux Mint and Windows (mostly Linux Mint). They are sometimes more aggressive at suggesting Linux than me.
The first defections will be relatively small numbers which probably would be overlooked by market research. Linux instead being at 2% is no running nearer 3% let say next year. But the 1% bump is primarily ex Windows users. In a few years that number could grow because they are actively switching many to Linux and suddenly there is an "unexplained and inexplicable" growth in Linux usage.