HDMI Licensing today said a forthcoming version of USB Type-C will allow for cables that push video from USB-C directly to HDMI.
The HDMI 1.4b spec includes a profile called HDMI Alt Mode. This lets the compatible host device push 4K video and 3D sound via the USB-C port to an HDMI-equipped screen or monitor.
HDMI Licensing said both the host device and cable need to support the spec, and it cannot be added after the fact (no software upgrades for older devices.) Even so, future phones will be able to plug directly into HDMI devices without the need for a separate dongle/converter.