> one of the things I would like to see in my lifetime is somehow it should be easier to "run the whole enterprise" from one box. Sure, it will probably be seriously underpowered and I can't do all things at once but for most small to mid-size companies, it should be possible to run all our "code" from one machine.

I think that's the mainframe idea. There's probably some interesting philosophical question in there about whether or not a data center is just a big mainframe. It sort of feels like it verges on semantics.

> Sure, there is no machine in the world that can fit all of YouTube videos but there is no reason why we can't have YouTube, with a limited set of non-production data, running from just one box. Thoughts?

I'm not sure what you mean exactly, but if you're streaming YouTube's traffic through one box (even if that box isn't directly connected to the disks on which the video is stored) you'll run into I/O bottlenecks--such a machine would need to push terrabytes per second which is probably not trivial. Moreover, having a single machine that can handle YouTube's peak traffic probably means you're underutilizing it most of the time.

You have a misconception about the workload of your typical database server. It's not about the amount of data it's storing, it's about

1. compute and memory bandwidth to serve complicated queries 2. IO

You can't scale memory bandwidth beyond some pretty low limit on one machine. You can't scale IO bandwidth beyond some limit. To give you an example, I've seen database servers with 20GB of data being so overloaded by compute requirements of complex queries that they needed to be scaled horizontally.