Beanie Babies -> Blockchain -> AI -> Quantum Computing.
I was about to make the joke that the next one in the chain would be a "bubble bubble". There have been bubbles around tulip bulbs, fiber optics, milk bottle caps, ".com". The joke was going to be something about how the next bubble would be a "meta bubble" - a bubble fed by hype over how "great" whatever the next bubble is going to be. But just as I was about to make the joke, I realized it wasn't actually implausible. That could literally be the nature of the next bubble.