I’m not 100% sure I agree with it, as much as I would love to. Eventually, yes, the word is going to get out and people are going to understand that it’s just as hard (if not harder) to be a bestseller in self publishing than it is in getting an agent and selling a book the old fashioned way. But at the same time, there will always be midlist authors (or big name authors) who jump ship and decide to self publish, and reap all the rewards and act like this is great and anyone can do it, ignoring the fact that they had an audience that a publisher built for them ahead of time, and that their success is not really one can translate to everyone.
People will always want instant gratification, people will always feel spurned by rejection letters, and people will always think that their story is the one that is going to be a bestseller and make them rich no matter what. And since it’s beyond stupid easy for them to do it self publishing, it will always happen. So, unlike the tech bubble (which required VC to keep it afloat) the cost of entry is 0. Nada, nothing, and so people will always risk it.