AudioMedia II has normal digital I/O, so you can use it with many converters if you like. The Sound Accelerator has some custom connection to a breakout box.
As for upgrade culture, you're very much right. It goes way back - I actually saw a website on archive.org that referred to NuBus PT systems as "antique" - in 1998, not more than two years after the first PCI system was introduced! But at least with this era it's still possible to get things running, and a lot of software has been saved. It'll be hard to impossible to recreate a 2023 DAW in 2043: everything is subscriptions and web-based activations.