ETA Prime on YouTube often covers very small form factor PC's which would be more than up for the task (dependant on budget), but as @AB_IT and pthers say, it's not much help unless you have the software to run a good front end that will allow for multiple streaming apps + other sources.
I made quite a few media PC's back in the day, but once smart TV's, PVR's and other set top boxes came along then it all went a bit quiet on the media PC front, which is a shame as they were great fun to setup.
I'd love to get one of these, but I have no idea what I'd do with it now that my TV provides all that I need media wise.