It has been over one year, and yet Windows 10 is far away from reaching 1 billion device
Windows 10 was originally unveiled on September 2014, and it became available on July 2015 which means it has been over a year. In this period, it was updated for many times and most importantly, it is not free anymore.
As of 26 September 2016, it reached to 400 million devices. Even though adoption rate to the current generation of windows was 115 percent faster than 7, it looks like Microsoft will not be able to reach 1 billion device by 2018.
When it was free, it was gaining about 30 million devices per month whereas this number is only 16.6 million per month now.
Unless there is a special attempt to fasten the adoption rate, we except win 10 to reach this number by 2019 or even 2020.