Maybe there is an approach using something like BoxedWine, to have a stable user-facing system that can be 100% ported to new hardware or underlying OS?
Maybe there is an approach using something like BoxedWine, to have a stable user-facing system that can be 100% ported to new hardware or underlying OS?
The most important thing you will need is to access digital banking and government services. These apps already requires you to have an updated and locked-down system.
If you disregard that requirement (let's say you'll replace a tablet periodically, just for banking and government services), the next important thing you will need is communication. That means an updated browser that can open the future generic wordpress-based website, discord, twitter or whatever platforms will be popular when you'll be old. These platforms already require an updated browser, and updated browsers require updated OS, which require updated hardware too.
You don't actually need a "completely stable computer system". What you need is a secretary.
No-one cares if the underlying architecture changes, so long as the user facing experience remains stable.
Actually, there's another way to do it. It's what I am doing, I just didn't realise it until now. :)
Reserve a room in your house for your own computer history museum. Use old systems, running old software, doing old tasks that you learned years ago. Never update, never upgrade. Each time you need something new and it doesn't work anymore on the systems that you have, buy another new system and add it to your collection. Keep using it for that task and newer, while continuing to use the old systems for the old tasks. Virtual machines work too.
It sucks, but the repeated aggravation of broken expectations is worse.
That doesn't mean it stops working, and I know there are plenty of communities providing unofficial support for old Windows and even DOS. The situation with Mac may be similar but smaller, just due to relative popularity.
This is less of an issue for DOS and Windows 95/98 because software in that era was offline-first.
The user computer remains unchanged through the decades. The interface computer is updated with all the security updates, and communicates requests back and forth between the user computer and the internet, ensuring format compliance. It also contains software to convert file formats from newer version to the user computer compatible versions (where possible). For example, converting Word document format to some old version.