I've recently been fantasizing about something like this, but in laptop form. Have a dedicated console/display node, a few compute nodes, a 'router' node, and a gige (or 10gbe) fabric connecting them.
I was looking into getting a cheap laptop recently, turns out you can get a decent one for €200 nowadays (probably less in the US), which outperforms and outprices anything you can build with cheap ARM chips. A decent laptop-sized screen is already €100, and the whole PiTop setup (HD display, RasPi 3, 6-8 hour battery, case, touchpad, keyboard and charger) costs $320. The €200 laptop outperforms it and even comes with a Windows 10 license. And no crapware as far as I could tell.
With a 32 GB of RAM and a beefy x86, you can have a fairly decent cluster inside your laptop. Even a fully configured Macbook will probably be able to host a dozen gigabyte-sized nodes, if you refrain from running Slack and iTunes.
Sure, and I have that in each of the half-dozen ThinkPads laying about my place.
That doesn't negate a desire for a unique architecture portable.
edit: Particularly of interest to me is being able to isolate nodes. Your router and console are on the same physical board perhaps, but only interconnect via an onboard Ethernet switch (itself managed as a 'slave' under either the router or console node, depending on where one landed philosophically). Compute nodes could be powered off entirely when not in use.
