The reason Nintendo moved on from conferences had nothing to do with outgrowing them, which is something the fans have peddled since the start to defend the decision. it was made because Nintendo kept screwing them up, cringe, waggle, tech issues on stage, poor scripting, and several other negatives and Nintendo moved to direct to have small talk on games and just show the gameeplay afterward or the trailer and then closeout.
Sony didn't start moving away from conferences until two bad E3's in a row, the worst being E3 2018. They produced their own conference which they expected to be so big they actually had it play at theaters as an option which didn't work out, but they got enough views and engagement to where they do these periodic streaming events that work out, but they are still restricting their reach by not showing up at least at one event as well.
With that said, the streams have an audience and they can control the narrative and messaging better if they use their own streams so they won't be going anywhere.
About E3 though they say it's being revamped and will change how it works, so maybe that will get Sony and Nintendo to jump back in.