Microsoft's current Windows 10 Insider builds have versions of the Edge browser that support extensions and for users on that build things just got a whole lot more interesting: AdBlock and AdBlock Plus are available through the Windows Store.
Ad blocking has been a native part of Windows for a while now - even if most people weren't aware. Tracking Protection can be enabled on Internet Explorer and controlled site lists can be added from a number of providers - including AdBlock.
However it isn't a particularly easy feature to access, even if you know about it and as a result it hasn't been a particular well-used feature. However, Microsoft are imminently going to push this functionality from Insiders to Windows 10 users at large. Given that 300m users are on Windows 10, and that they will be well aware of both the Edge browser and Microsoft Store, I'd suggest that a lot of users will be adding two and two together and getting ad blocking enabled in Windows 10.
This starts to be a big concern for publishers, who have yet to show that there is a viable alternative to ads for funding their lavish productions. If they can't keep the income rolling in there's no doubt that there will be more and more publishers closing their doors.
There are publishers who have wound back on their advertising in recent months, but they are likely to be swept up in the backlash against sites who have re-doubled their efforts to push more advertising messages to fewer web browsers.
Some sites have started barring their content to users who have ad blocking enabled - giving them the option of subscribing or unblocking the site. I'd guess most of the users disappear.
Some never to return.