Algorithms from Platforms will always filter out content that people don't want to see.
Facebook/Instagram will definitely keep increasing its MAU, but usage will drop and people will focus on higher value entertainment (think Netflix, real life experiences etc).
The fact people tend to use their Tiktoks and reels a lot, it's because they are poor or don't have anything more interesting to do, you'd see people consuming less, but still being active and doing whatever is new and interesting.
The "web" as some tech people perceive it and have nostalgia, like searching through a search engine to get to a page and content has been dead since a long time. Most people don't use that way, they use the internet through their phones and typically directly from Apps.