Agreed that WSUS is a horrifically underdeveloped nightmare. But, this is not the answer. The answer is modernizing WSUS or replacing it. There's nothing wrong with having better tools in Azure with an attached price tag. The problem comes from emptying the niche that WSUS occupies.
People need to stop thinking about this as, "I will approach this news on my systems with..." That's not the problem. Of course, you will come up with a solution that works, and of course you will keep your systems patched. That's not the point.
There are organizations out there that do all sorts of things that would make no sense to you. To try to keep this short, let me just say that I have had to set up "rogue" WSUS servers to ensure that some things got the necessary patches in order to get around malicious/incompetent decisions made at higher levels in IT. No, it doesn't make sense for anyone to ever have to do that. But, those organizations exist, and those solutions are necessary.
When WSUS goes away, then, in those organizations, the malicious/incompetent people will decide who gets automated patching at all, and what automated patching they get. I would guess that admins at lower levels might still be able to manually patch or set the servers up to get patches directly from Microsoft. But, it's clear that they're not working in a friendly environment. Somebody is going to miss something. WSUS isn't a silver bullet, but it's something, and it's an easy something.
Realize right now that there is a 100% chance that one or more of these organizations has your personal information, credit card numbers, health records, all kinds of things. As soon as WSUS goes away, there's a 100% chance that your data will wind up on a system that the organization didn't want to pay to patch, somebody in subordinate.IT.company failed to properly beg someone in IT.company to patch, or OOPSIE somebody didn't check the monthly patch result on. The risk is bad enough with WSUS. Again, look up Melissa and SQL Slammer. I forgot MSBlast, that one had a patch available before it was ever exploited, too, and still caused all kinds of drama. Anyway, the point is that it doesn't have to be a system that you're responsible for to become your problem.
The end of WSUS is a gift to attackers.