It's already possible to make an MP3 player so small you don't want to use it for lack of a human-scale interface. Same for phones. They have more capability than you can access through that tiny screen. And don't get me started on trying to dial or type when you have adult American male-size thumbs.
So some devices are already constrained not by what is possible, but what is comfortable. Assuming it were possible to plug your PC directly into your brain, and have fully-immersive sound and video, would that necessarily be the interface we want all the time?
As I'm typing this, every now and then I stop to think, and I look away out the window at the snow. I want to be able to look away. Sure, I'd like a bigger TV, but I don't want it to dominate my living room.
Connections will keep getting faster, compression better, screens larger, CPU/GPUs faster. Every so often a Jobs needs to remind everyone the difference between more and better. But there will be more, if only so the non-Jobs-es can try to compete.