I don’t know the name of the trains that are meant to replace those 70’s trains. But there are options, truth is that it is just aging and is increasingly hard to maintain them in decent condition (most recent modernization was ~2015). At least here it will be replaced eventually for more modern ones, I know it is blast from past but it just doesn’t matter for regular commuter.
Yes too small, too slow and on electrified tracks irrelevant. They are meant for small regional lines, not for suburban transport. It is like running trams as EC trains.
Had to look at wiki about the modernization of 810.
And I wasn’t entirely correct the true modernization was performed 2005-2012 basically rebuild to be the yellow RegiNova train.
Last “modernization” 2020-2024 was pretty much stopgap before they can get some new trains. Fitted new motor so AC can be fitted and new interior.