Such a standard exists now; it's relatively new and not widely adopted, but both standard USB-C 3.1 (which includes Displayport-over-USB-C) and Thunderbolt 3.0-over-USB-C can do exactly that (although you don't get native Ethernet as far as I know; in the thunderbolt case, you can use a full-speed PCIe ethernet chip on the PCIe part of thunderbolt, and USB 3 ethernet isn't too bad.)

For that matter, in theory Displayport (1.2) can do everything except power, although it's embarassing how long the spec for USB-over-displayport has been around for how few monitors support it. I thought there was a USB-over-HDMI spec, but I can't find it. There's even an ethernet-over-HDMI spec (not supported for Displayport) although I'm not aware of anyone supporting it.)

I've got a USB-C 3.1 dock (with displayport-over-USB-C) for my work laptop, and the only reason I have a second cord (HDMI) plugged in is that the Linux drivers for my laptop don't support displayport daisy chaining and the spliter in the dock won't do two 2K monitors. Daisy chained in Windows, they both work.

USB-C seems to be what the industry is converging on, and I think in a couple of years you'll be able to get a mini desktop that does exactly that. Whether you'll be able to get a monitor with (in essence) a built in dock for it to connect to... that's anybody's guess.

That also said, if you use a VESA mount and get short (1'-2' or 500CM) wires, two short wires for HDMI and USB* plus an external power brick aren't too bad...

[* assuming a real monitor with a hub built in... or just use wireless everything and either BT or a logitech unifying receiver.]