Thinking about whether I'll upgrade my next PC partway through its life
There are some people who routinely upgrade PC components through the life of their (desktop) machine, changing out CPUs, memory, graphics cards, and close to every component (sometimes even the motherboard). I've never been one of those people; for various reasons my PCs have been essentially static once I bought them. I'm in the process of planning a new home and work PC, and this time around I'm considering deliberately planning for some degree of a midway upgrade. Given that I seem to keep PCs for at least five years, that would be two or three years from now.
(Part of my reason for not considering substantial upgrades was I hadn't assembled PCs myself, so thoughts of things like replacing my CPU with a better one were somewhat scary.)
Planning for a significant midway upgrade in advance is always a bit daring and uncertain, since you never know what companies like Intel are going to do in the future with things like new CPU sockets and so on. Despite that I think you can at least consider some things, and thus perhaps build up your initial PC with some eye towards the future changes you're likely to want to make. Well, let me rephrase that; I can think about these things, and I probably should.
However, for me the big change would be a change in mindset. My PC would no longer be something that I considered immutable and set in stone, with me just having whatever I had. Merely deliberately deciding that I'll have this mindset probably makes it more likely that I'll actually carry through and do some upgrades, whatever they turn out to be.
In terms of actual upgrades, the obvious midway change is an increase in RAM and I can make that easier by picking a DIMM layout that only populates two out of four motherboard DIMM slots. These days it's easy to get 32 GB with two 16 GB DIMM modules, and that's probably enough for now (and RAM is still surprisingly expensive, unfortunately).
Planning a midway CPU upgrade is more chancy because who knows if a compatible CPU will still be available at a reasonable price in a few years. Probably I'd have to actively keep up with CPU and socket developments, so that when my PC's CPU socket stops being supported I can wait for the last compatible CPU to hit a suitably discounted price and then get one. If this happens too soon, well, I get to abandon that idea. It's also possible that CPUs won't progress much in the next five years, although I'm hoping that we get more cores at least.
Graphics card upgrades are so common I'm not sure that people think of them as 'upgrading your PC', but they're mostly irrelevant for me (as someone who runs Linux and sticks to open source drivers). However I do sometimes use a program that could use a good GPU if I had one, and someday there may be real open source drivers for a suitable GPU card from either AMD or nVidia (I'm aware that I'm mostly dreaming). This will be an easy drop-in upgrade, as I plan to use Intel motherboard graphics to start with.
(Hard drives are a sufficiently complicated issue that I don't think they fit into the margins of this entry. Anyway, I need to do some research on the current state of things in terms of NVMe and similar things.)