Actually, I don't think you were the only one thinking along these lines - well, not exactly the same idea, but still: There's a new type of USB connector called USB Type-C. It's a reversible (it can be pluged in backwards and function the same) connector that can carry video, ethernet, power, and all existing USB data, and is about the same size as existing micro-usb connectors (the kinda used by smartphones). It is rated for up to 100W and data speeds of up to 10Gb/s. It will almost certainly be added to Ara devices, and is already present in the two latest Nexus phones (5x and 6p), the Chromebook Pixel, one of Apple's MacBooks (don't remember which, but the only other port on the computer is the headphone port if I remember right). The OnePlus 2 also features a USB type-C port, but does not take advantage of any of the new features for USB Type-C aside from the connector.
Older versions of USB Type-C may be connected through adapters, as well as video out for connecting to external monitors. I am very excited to see what this new USB connector will offer.