Even though I generally like the sentiment, replacing the cat-5 cable with a newer one should be a pretty fast task, and wired ethernet always is better than wireless.
The right future oriented mindset in terms of building a house would be to make it easy to install wires. Or pipes. Or whatever.
Just in time hardware is only useful if you have a place to put it. That’s the tricky part; trying to figure out how to make sure you stay compatible with whatever new stuff comes along.