I strongly suspect it just announces itself.
"N123FOO DECLARING EMERGENCY; PILOT INCAPACITATED, AUTOLAND ENGAGED; CLEAR RUNWAY 21L; 12 MILES OUT" sort of stuff.
(It'd probably also be significantly more expensive, due to the need for a subscription.)
But I could imagine a company contemplating building the remote-pilot-for-emergencies service might be scared off by potential liability. Families of pilots killed in GA accidents routinely sue aircraft and engine manufacturers even when the FAA determines the cause to be pilot error.
Remote truckers in an office, similar to a UAV drone pilot.
Possible scenario: if pilots are already sitting in a simulator for currency training / testing, it may be possible to have the sim be 'reset' to a live feed in an emergency.
You wouldn't have them hang around 'just in case', but rather use people who are already present for some other reason.
Another possibility: pilots are hours-limited for a given time period. If you have pilots that have hit that limit, some may be willing to spend time in a ready-room for a nominal bonus.
This is not an option in a plane. If it was, this technology wouldn't be needed - if the pilot is incapacitated just brake to a halt and step out of the plane...
Starting at 1:30, "NOVEMBER SIX HOTEL LIMA, POSSIBLE PILOT INCAPACITATION, SIXTEEN MILES WEST OF KILO CHARLIE LIMA--" at this point the voiceover talks over the announcement, and I have trouble making it out, but I'm pretty sure I hear a "...LANDING ON RUNWAY..." in there as well. For those of you that don't know pilot jargon, that's the plane's registration number (N6HL), the situation, location relative to the nearest airport (KCL-something), and what I'm pretty is a declaration of intent to land on a specified runway.
So, your guess is correct, what the system does is announce its status and intentions and let ATC clear the way.
Other comments have speculated about uncontrolled fields, but I think that's less likely to be an issue. Per the demo video, the auto-land feature requires a GPS approach with altitude guidance published. If a field can't afford a staffed tower, would it be able to afford to have a published GPS approach with altitude guidance? My intuition says no, but as I'm not a pilot, I could be wrong about that. On possible scenario I could see is that the tower isn't 24x7, and so the field is uncontrolled at night. Perhaps such a field would have a GPS approach published, and if the auto-land selected that field, it would be up to any pilots in the area to be aware of the announcement and get out of the way. AFAIK, having one of your radios monitoring the emergency band is considered best practice, so other pilots in the area should be able to hear the emergency announcement and react appropriately.
But at this point, I'm speculating as well. For all I know, the auto land only selects airports known to have a manned tower at the time of activation.
The accident plane will be constantly reminding people of its status on this frequency when there isn't a tower. Other pilots will be talking in response to each other but this system can't understand what they're saying. So it will just explain periodically what's going on. Something like:
"Springfield Traffic, November Six Zero Hotel Lima with Emergency Possible Pilot Incapacitation. Final Runway One Six. Full Stop. Runway Will Close After Emergency."
I can definitely imagine, especially when this technology is new, other pilots trying to ask questions
"Zero Hotel Lima, did you say runway will close? I was planning to land there after you. Do you know when it will re-open?"
The system can't understand their question and won't answer, but their training should teach them De Niro's line from Ronin. "When there is any doubt, there is no doubt". Something is wrong, they should divert and leave the emergency plane to do its thing.
The vast majority of reasonable places to land something small like these $2-3M planes will not have a tower at all, and for some of the rest the tower is only part time, but your emergency may not be, so it is usually going to be talking on CTAF and other pilots will just have to make new plans to work around the emergency.
Which would suggest that if you need to be vectored to a runway, the aircraft can negotiate that with ATC automatically (and perhaps ATC can advise which is the most appropriate diversion?) This in the situation where the pilot is incapacitated, but the aircraft isn't in an immediate risk of crashing (e.g. you're cruising, but there's bad weather immediately below you).
It should also be able to use stuff like D-ATIS to get airport conditions.
That seems optimistic though, perhaps it just announces its intentions and hopes ATC clears a path?