on the uncompressed front HD-SDI, one standard coax cable, one standard 75 ohm BNC connector, and standard HD-SDI switches, DA and Matrix switches vs all the odd ball HDMI crap. Even better, 3G-SDI interface consists of a SINGLE 2.97 Gbit per second serial link and is standardized in SMPTE 424M, supports 4:4:4 @ 2K resolution on 1 coax 75 ohm BNC cable. all of this is standard broadcast industry equipment, the HD you are watching at one time was highly likely shipped around over HD-SDI.
To Chris's point on the compressed front I don't see any reason that existing modulation (ATSC, QAM, etc) standards and codec's (mpeg2/4, etc) over standard coax wouldn't of worked well or adapted to CE displays and equipment vs HDMI. A good basic example of this was the the old ATSC module that dish use to sell for their HDTV STB. You had your DISH HD STB and instead of hooking up a component cable, you just had one standard coax with f connectors that you just ran into the Antenna F connector on your TV and you could run to multiple displays that had ATSC demodulators using basic cable splitters. I understand the the content providers had issues with this, but I dont understand why they couldn't of just developed an encryption wrapper, oh that is right they did encrypted QAM.
Most if not all this existed and predated HDMI, worked with standard gear and it seems to be just needed to be cleaned up a bit just to be a little bit more CE compatible, instead it feels like we got the HDMI mess.