I was about to write a small essay on how everything from monitors to speeds seemed to be stagnating.
But I actually think there is a chance we might gain two new revolutionary[1]ish ways of interacting with computers within the next decade.
LLMs might truly bring us talking computers. Siri is old, and current AI is a fair mix of real advancement and overhyped, but once the dust settles, I wouldn't be surprised if a significant chunk of the population talks with their computer.
XR devices will likely keep shrinking and I figure somebody will find a killer app for them eventually. 20 years ago, a computer sat on a desk. Today I have one in my pocket. I wouldn't be terribly surprised if in 20 years, I have one in my glasses.
Of course, all of this is speculation. And I don't think the PC is threatened, but it will probably face competition from new ways of using computers.
[1]: As in different and not just slightly better than last years model.