It might not be the best solution for gamers, but having a monitor attached through USB is quite a practical solution for most purposes. After all, virtually every computer has a USB-interface, while video inputs vary greatly. At the San Francisco CES, DisplayLink showed its new DL-5500 series USB-chip. This is a product that will be implemented into various docks and adaptors by several manufacturers in the next months.
4K over USB 3.0
The advantage of the new DL5500 UHD-adaptor is that your computer doesn't require a special connector to utilize the full potential of a 4K-monitor; a USB 3.0 port and a modern processor are sufficient. The latter is important since the technique requires quite a bit of CPU-power.
DisplayLink's adaptor with the new DL-5500 UHD on board