A couple things to note here.
1. Why do you need iTunes? Make your music library local if you haven't already and ditch it.
2. 7 is definitely on its way out, but 8 is still kind of a special case since it will be receiving official security updates for a couple more years still. The real breaking point will be drivers, but if people can still find a way to make Windows XP work in this day and age, I don't think that will be too much of a problem. As to Discord, I use that in a browser and on my phone anyway, so no big loss there at all. NVidia/AMD would be a big factor, yes, but the 30 series of current NVidia cards all support 8.1 and even 7, and I know at least with NVidia, they don't start dropping OS support until at least a new line is launched. They could have ditched 8.1 for this 30 series, but they did not, so that also gives 8.1 a few more years of life behind it.
3. DirectX12 has been a bit of a thorn in the side of legacy Windows users, but Vulkan is starting to catch up fast, and Vulkan is OS independent. Perhaps the biggest standards that 8.1 is really missing is support for the latest Bluetooth standard of 5.2 (meh) and Wifi 6, or 802.11ax (more of a problem, but also not a big deal).
4. Finally, even if all this didn't apply, it's still not all doom and gloom. Quite the opposite. There's a reason that Valve has been on a rampage with providing Linux support. They got mad at Microsoft a long time ago and didn't like being beholden to them (think it started with the bul***** UWX), so they're now funneling their money and efforts into Linux to give it a massive boost in compatibility. And it's helping. A lot. This is also probably why Valve dropped Steam support for Windows Vista and below. They believe in and want those people on Linux instead. Back in the day, Linux used to be frustrating to use, and compatibility equally so, but those days are long gone, and in some instances, Linux actually works BETTER than Windows. And even further, it's only going to improve. The kernel has shown itself time and time again to be absolutely amazing for old hardware while still retaining full support for the latest hardware and drivers, now easily auto-detecting what needs to be used and doesn't and seamlessly applies the correct drivers without any input needed.
At the very end of the day, even if Windows 10 didn't suck, we all knew this was gonna happen sometime. OSes get old. New standards are developed. That's just what happens. But just because 8.1 will reach end-of-life sometime is not the end of the world since Linux is now the looming behemoth over Microsoft's OS division, and if Microsoft doesn't shape its a** up, that penguin is gonna start stealing a lot of f****** market share.