Lack of OR support would not kill the game.
Lack of "immersive" cockpit headlook menu tomfoolery would not kill the game.
Lack of PvP would not kill the game.
Funny how people see some things as dispensable, whereas others see them as essential! Lack of external views
would "kill the game" for a certain set of players. Camera viewpoints are really important, and very subjective. I've had numerous otherwise great games I've had to abandon purely because I find the camera objectionable - either it's too close in, or it's locked looking too vertically, or whatever. If it's a solo game often there ends up being an unofficial camera hack but we don't want to go that route here!
I don't suppose a complete lack of any form 3rd person would kill ED for me, I've bought in too heavily for that, but it would be really really disappointing. My list of disappointments has grown rather too large over the last year, sadly

[for ref, no PvE mode, no 3rd person, no HUD-only/cockpit-free, menu mucking about rather than keybinds... : these were all - to me - surprise design revelations made after the KS ended].