Did XMPP win?

That remains to be seen. I'll gladly accept XMPP as a point in the "against" column, as it has a long way to go, if it succeeds.

Google succeeded handily at their last round of embrace, extend, extinguish, against XMPP, by dropping support from Google Chat.

It's worth noting that the question isn't really whether XMPP replaces WhatsApp, it's whether it can unseat SMS.

SMS is seriously entrenched. I don't know it's state of openess. My understanding is it's mostly run/owned by a few large proprietary players.

https://en.m.wikipedia.org/wiki/SMS

Again, I'm happy to concede that XMPP looks doomed today, like RSS did a couple decades ago.

Did RSS win?

RSS certainly hasn't won, yet. But RSS is doing fine, behind the scenes. Most of the RSS the average person interacts with doesn't look, to them, like RSS. There's a lot of RSS still in wide use, today. Competing solutions are currently enshitifying (Google Search, Reddit, Facebook, Xitter), while RSS is still free and still just works.

That's not an automatic win for RSS, until you consider that RSS has already outlived WebCrawler, Digg, MySpace and GeoCities, among others.

I'm calling it early in favor of RSS.

We've agreed that I am prone to do so, though.

Did Linux win?

Yes. Linux won. The vast majority of computation today runs on Linux.

Windows used to hold a serious percentage of web hosting. My best guess is it was around half. The current percentage is unknown, but generous estimates put it at 3%, at most. For some context, the Azure cloud (Microsoft's web hosting that Office 365 runs on) is known to mostly run on Linux.

But to address the other part of your question:

Is Windows desktop going away?

Something mostly proprietary that costs money and is called Windows with be with us for a long time.

But the Windows kernel is counting it's final days now, while most people haven't noticed.

The Windows kernel is cool, but it's a pure cost center and no longer offers anything that Linux doesn't.

Game developers noticed, this year. I personally, held onto Windows desktop for decades, solely for gaming. I suspect the shift this year will turn out to be a key moment in the spin down of the Windows kernel.

A desktop OS has a ton of moving pieces. We're currently seeing the natural trend for those pieces to take advantage of existing open solutions.

I predict that we will see more and more of that, until the switching cost reaches the current low cost of switching web browsers.