You're factually correct, but missing the point.
Microsoft said they'd provide security updates for Win7 until 2020. Period. There were no caveats like, "Except if you upgrade your hardware".
Consider this. Apple is a hardware company. They tell you up-front-and center, "Your hardware will stop being supported by our latest and greatest OS releases after some number of years." This is because they want you to buy new hardware after a while.
By contrast, Microsoft is a software company. They could tell you, "Your software will stop being supported after some numbers of years if you get the latest and greatest hardware." That would be okay to do if they let you know up-front.
But no, they pulled it out of their hat AFTER 7+ years. My personal belief is that they are so freaked out by the slower-than-expected uptake of Windows 10 that they are willing to piss off a lot of their base to try to force people to adopt Win10.
This is not policy or strategy. This is strong-arm tactics.
Trump to meet with Bill Gates on Monday.
No one expects Win7 to work on all modern hardware. Indeed, my company has bought modern computers that come with Win10 drivers for the I/O, and Win7 won't run on those machines until you find the appropriate drivers. We've all been there before.
But withholding security patches that were promised until 2020 is something else entirely. That's blackmail, or a thinly-veiled protection racket.
True, they never said it would work on all new CPUs forever. But neither did they say they were going to break an important promise to their customers.
I believe you're right. Look at this chart. Win 7 and XP users still outnumber Win 10 users by two to one. Granted, the number of Win 7 and XP users goes down every month. But very slowly. Which is frustrating to MSFT no doubt.
I have read that Win 10 has had the slowest adoption rate of any MSFT OS. Interesting chart from here: