- participants will predominantly look around in 360 degrees
- participants will be manipulating the objects they’re seeing projected in 3D
- participants will have prolonged engagements with virtual objects
- all people present in the room will also be interacting with the same virtual objects
If these are all true then your analysis is correct: headsets are the only way.
If all of these presumptions are at least somewhat false then handheld “opera glasses”-style AR experiences will be very popular.
Personally, I think even people who have headsets and spend a lot of time in VR will also use handheld displays, for transient use and when others are present.
From cack-handed (inept; clumsy)?
You can't just come out with glasses because there is too much you don't know about how multi-user and persistent content AR interface and communications work from a standing start.
And yes, I think Niantic are more of a technology / platform company than they are a game developer, and I think that's the level of their involvement in the Wizards Unite game.
Google "just came out with glasses", but that didn't go very well, probably for the reasons you gave. Google Glass time may be upon us again soon, however, given these tech demos.
It's like playing a shooter game in the real world, but having to have the device pointing in the right direction in order to see what's actually there. Like using a torch in pitch blackness (Doom 3). This is where a Google Glass / VR-style headgear kind of interface would be perfect.
But since this is all just in "tech demo" stage, I'm probably being too critical. It is "cool".
Tertiary worry: AR advertising.