Smartphones replaced laptops. A huge amount of people don't own a laptop or desktop PC - they do all computing via smartphone or maybe tablet. My wife almost never opens her laptop, nor does my mom
It is hard to say when the peak of laptops in circulation was, right? Because simultaneously the tech has been maturing (longer product lifetimes) and smartphones have taken some laptop niches.
I’m not even clear on what we’re measuring when we say “replace.” Every non-technical person I know has a laptop, but uses it on maybe a weekly basis (instead of daily, for smartphones).