I think it is probable and possible to fire 8 rounds or more into an enemy combatant, or other human threat in the time its takes them to die. It happens frequently with a number of different types of ammunition... especially with penetrating ammunition. That’s why people and agencies with the freedom to choose ammo steer clear of penetrating bullets for the most part. The army chooses what it feels it needs most in a cartridge which is penetration. Considering cover and potential body armor, penetration can still kill in more situations than expanding and fragmenting rounds.
With the new ammunition, you can assume that it may still take more than one shot before a threat is stopped in a small room, but if they get the 6.8 up to 5.56 velocities, the wounds will be pretty nasty.
From all the articles referenced here and other places, seems like the army is more concerned with increasing the effectiveness in distance and against body armor and not so much with extremely close quarters.
I’d have low confidence using green tip at close quarters on unarmored threats, as davidsog’s own experience illustrates.