SMEs won't touch it because of the privacy concerns. Corporates who have access to the full privacy features in the enterprise version are still suspicious of it.
Its main USP for the general public is that it's not as bad as Win 8 - which hardly seems like a win at all.
I'm happy to use Linux for some applications, but realistically I think most Windows users who are switching will move to a Mac.
Personally, I'm keeping well away from Win 10. The one machine here with Win 8.1 isn't getting upgraded - ever. I may even downgrade it to 7.
I haven't seen enough to make a firm prediction yet, but I do think if MS can't get a handle on these update and privacy issues very soon and they increasingly become the story instead of any of the new features, the writing may be on the wall. Microsoft seem to have attracted some overall positive reviews at launch for Win10 in the general press and non-geek PC sites/magazines, but a lot of that positive early coverage is getting drowned out by concerns about reliability, privacy, and whether the relatively few big new features (Cortana, Edge, DirectX 12) are actually worth much anyway (with, respectively, questionable effectiveness, lack of plug-ins, and few if any games available that take advantage of it any time soon, among other challenges). "It's not as bad as Win8" is not a pitch that is going to support sales for the next several years, particularly when so many of their business customers are still on 7 anyway and have nearly 5 more years before they're going to run into end-of-support issues and be forced to act one way or another.
Microsoft seem to be throwing everything into cloud and services and mobile-friendly software and new devices, at the expense of solid server/desktop/laptop software that until recently has generally just worked and aside from the occasional blip stayed just working for a long time. Which of these areas has historically yielded Microsoft's more successful offerings, and which has had a string of disappointing results? Exactly.
I think if anything it would be users accepting this strategy by installing the new OS that would be the death knell for privacy on the PC. So far, it doesn't seem clear that this will happen, though.
The reaction from business is predictably hesitant anyway. Some of the concerns about Windows 10 won't apply so much with the more business-oriented versions, but in any case it seems likely that large organisations are going to do their homework, other than maybe a few high-profile early adopters who may or may not have been offered unusual incentives in return for being flag bearers.
As for home users, there was reportedly a post from someone on the Edge team a few days after the launch that gave some figures about adoption generally. They looked quite impressive at first sight, but if you extrapolated from the reported adoption rate, it would still take a substantial increase or a very long time to shift the market as a whole onto Win10, despite all the incentives and nag messages and free upgrades Microsoft have been pushing this time.
The one tiny data point I can contribute myself is that based on analytics I just checked for a consumer-focussed site I run, Edge hasn't even moved the needle on browser distributions this month.
So I'm not sure Microsoft get to sound the death knell for privacy on the PC. They can provide an OS that reduces privacy and raises concerns, but that doesn't necessarily mean people and businesses will choose to use it. Time will tell.