The only longevity issue is the battery, which is a limited lifetime part no matter what, and no support for the newest Xcode, which is unfortunate, but not a real limitation on what I use it for. It's something that I could probably work around by using opencore.
Its kind of crazy TBH. A 2004 macbook (powerbook?) would have been genuinely outdated in 2014, but in 2024, my 10 year old laptop is... fine?
Same thing with my phones. I went from an iphone 4, to a 5, to a 6 to an 11. And there I have stayed. There are a few features that would be nice to have, but not enough for me to fork over the cash. And my old one still does everything fine.
The real limitations are the incompatibilities with new APIs. I fixed up an old macbook air I found at a recycling center for a friend's kid (2011?) and getting it setup took some time since the imaged version of Safari incompatible with modern HTTPS. Once I cleared that hump, though, it was a great machine for youtube, browsing, etc...