Technical hurdles for high-frequency video output implementation
What I've seen normally done is to use multiple lines.  For example, high-end high definition video cameras (like the Sony F55) use multiple 3G-SDI lines.  Even though in those cases it is usually for very high resolution (4K) at nominal frame rates (60fps), you could use the same technique to increase frame rate (240fps) at nominal resolutions (1080p).