As of now, we know that escalation protocol is public event like activity so everyone on planet can join.
But.They are hard. Really hard...
You said its ''ENDGAME CONTENT''
I dont want to run it with some random people without communication, but fireteam limit to exploration is set to 3 so ..... I hope there are changes to this
Hehe, dont tell me you didnt took this into consideration
Bungie's definition of Hard, isn't.
They tried to gotcha the Summit people they invited with this event, having already believed it to be hard, and they even gave the players under-leveled accounts to use. The result was the Summit players having given them the feedback that it wasn't hard enough.