Here's what I've discovered:
1. There may or may not be a USB to HDMI adapter released.
2. The nVidia Shield Tablet (Android-based) is ranked up there as the 2nd best (next to iPad) in terms of a tablet to use with the Phantom and it has HDMI OUTPUT! The HDMI output has little to no latency. It also has built-in GPS (16gb and 32gb versions) and LTE capability (32gb version). A few videos on Youtube tout it as a great tablet for the Phantom Inspire, etc.
3. Airplay may work, but Airplay has latency issues.
4. The best goggles seem to be the Headplay HD goggles about to be released (getfpv.com) as they are only $250 and support HDMI in, 72 degree FOV, and 1280x720 (exactly the resolution that the Phantom 3 broadcasts its live stream in).
I figure that this setup will keep me happy for awhile until they POSSIBLY release an HDMI output capability, in which case I can always sell my Shield (unless I grow attached to the Shield) and lose only a little bit of money, but keep the goggles.
The real fun begins when we start to consider if the winter release of the Oculus Rift will support 2D HDMI input. It probably will just fine. In that case, it will be 1080p resolution with over 100 degree FOV. And perhaps using the SDK, someone will program an app that allows the headtracker to control the camera view on the Phantom 3! Totally immersive.
If only had all this technology had been available to me when I was a kid. I would have been in heaven.