First, scale: Microsoft said in its blog post this morning that there are now 5 million Windows Insiders, up from 3.7 million in May. The company also said that it has collected “millions” of “reservations” for Windows 10 from the public. Both numbers seem reasonable.
Microsoft will offer Windows 10 as a free upgrade to Windows 7 and Windows 8 and 8.1 users for a year. The company hopes to land the code on a billion devices in two to three years, a wide band, but also a large figure.