Probably for 5.3.2 it'already possible to make one but as of now no one is working on it.Something like WiiMC or better
A media center with only text that can only load from sd would be useless for 5.5; that's basically worse than what nintendo's browser does. Also it would be very slow and I'm not even sure if it's possible to play a video without gx2 (using setpixel with a 1080p video with a loop that repeats 2073600 would take like 1 minute just for the first frame -_- ). But hopefully an exploit for 5.5 will come sometime, giving full gx2 and sd access. The better thing would be an IOSU exploit so we could access usb, sd and maybe even the bluray playerIt would probably have to be a REALLY simple design unless you can shine the kernel exploit over it (so we can have SD card access, maybe a GX2 GUI so it's easier to get around). A non-kernel version of the app will probably be stuck with the lame console GUI (just text-based interface) and you'll no doubt have to just load media over the network...
So in my opinion, it will probably happen some day, but not anytime soon due to the above facts.