Microsoft still updates the XP, Vista, and Win7 users who have paid for support, which is essentially the Enterprise versions still used on commercial systems. In theory they could still update the regular user systems, but that doesn’t make money when they are trying to sell new operating systems and software that only runs on the newest OS.
Keep Java disabled from the control panel menu and your chances for being locked by ransomware goes down to virtually zero.
Windows 7 is still in extended support and will continue to receive support until 2020.
As a business entity with an EA that covers a handful of legacy systems, I can tell you that while yes, they’ll help you if you have trouble with, say, Windows XP or Server 2003, the support is not what you might think. In most cases they outsource the labor to third-parties who have experts in those older operating environments. There are instances, however, where that support just doesn’t or can’t fix issues due to the functionality of the operating system itself.