One thing that people seem to be missing here is that wayland is being intentionally written to make it hard to do networking transparently .
Form the FAQ "No, that is outside the scope of Wayland. To support remote rendering you need to define a rendering API, which is something I've been very careful to avoid doing. The reason Wayland is so simple and feasible at all is that I'm sidestepping this big task and pushing it to the clients. It's an interesting challenge, a very big task and it's hard to get right, but essentially orthogonal to what Wayland tries to acheive. "
The other big thing people are missing is people will be writing apps for wayland. Simply putting X on wayland won't work to run those apps. Just like OS X has support for X but you can't run an OS X app over it.
The reason Apple and M$ don't have native network transparency is they are commercial platforms and the commercial companies that sell software to run on them want you to pay for each machine that runs the app. If everyone can run an app off one machine it eats into their profit margin.
The only real problem with the way X does networking is it sends large uncompressed bitmaps over the network. Running ssh with compression on can alleviate this to some degree.