My 2.5yo can open YouTube app on whatever device she finds on the coffee table and usually find content through suggestions. 8yo already got banned from YouTube by watching excessive amounts of Minecraft videos, until summer.
We hosted a reunion event for kids of close and distant relatives during the semester and 1/4 of the day spent on YouTube, a stat based on 5 kids ranging from 2.5 to 11.
I don't see any other platform reaching every kid in the world other than YouTube. Are there any? Google will sure monetize it better than today, all TV entertainment in the future will be consumed through companies like YouTube, Twitch etc. It's easier to see it if you live with younger people.