A lot about Windows 10 is still unknown, especially on the tablet side, O'Donnell said, adding that details relating to version breakdown, devices and pricing of Windows 10 remain unclear.
It's too early to predict the impact of Windows 10 on PC shipments, but it won't be as big as the kind of boost Windows 7 provided to PC shipments in 2009, said Jay Chou, senior research analyst at IDC.
Windows 7 came to market after Windows Vista, which was considered a debacle. At that time, PCs were dominant, but the market has now changed, with mobile devices being used as PC alternatives.
"Vista did not have to compete with smartphones and tablets," Chou said.
PC upgrades may first take place among consumers, as businesses test the OS and wait for initial kinks to be ironed out.
Windows 10 "is more amenable to power users, which is important for commercial upgrades," Chou said.
As Technalysis Research's O'Donnell put it, "Windows 10 finally gets past Windows Vista version 2, which was what Windows 8 was."
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