Microsoft could justify such an action if the widely-used Windows 7 was nearing retirement, but that's still four years off. (Windows 7 exits all public support on Jan. 14, 2020.) If it were to make this move, it would need to do so before the end of July 2016, or extend the free upgrade offer beyond the current 12 months.
It's conceivable that Microsoft would trigger an automatic upgrade if it felt its back was to the wall because of lackluster Windows 10 adoption or believed that without such a step it would fail to meet its publicized goal of putting the new OS on 1 billion devices by mid-2018. Currently, that's not the case.
While Windows 10's uptake tempo has so far not exceeded that of Windows 7's during the latter's first five months of availability in late 2009-early 2010, nor has its shortfall been significant. Meeting the bar set by Windows 7 has been a major achievement for Windows 10.
But the nuclear option is almost certainly on the table, even if CEO Satya Nadella said a year ago that the goal was to, "...move from people needing Windows to choosing Windows to loving Windows [emphasis added."
If Microsoft were to trigger an auto-upgrade, expect to hear rationales that evoke past arguments at prior steps in the distribution strategy, including: assertions that customers prefer Windows 10 over predecessors, with statistics backing up the claim culled from Windows 10's telemetry; and assurances the new OS is more secure than either Windows 7 or 8.1 -- historically true enough, as fresh operating systems are resistant to attack until hackers dissect the code and find new vulnerabilities or ways to avoid new defensive technologies.
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