I wouldn't say the internet is dead, rather that all the old imageboards and the websites that imitate them are going to die from inactivity. the demographics of the internet are different and the means by which people access it are too. Think about it, in the 90s to the early 2010s the main way people accessed the internet was through a laptop or desktop but nowadays it's being accessed mostly by phones. This then favors apps over websites when it comes to any type of social media resulting in less activity and by the time those people get a laptop or desktop they will have already settled into the current social media apps. Additionally, the internet is way less autistic now that normal people have to access it because it integrated itself into the rest of the world.