But...but...but...I want to play through Boromir's battle all the way until I actually die and earn those hobbits their freedom with attack rolls and exertion points!
I guess that could happen after the session so only the players that are interested get/have to watch.
To be honest, if it had happened at my table... I'd have the player narrate the heroic of his character.
But I feel that heroic sacrifices are much more common in films and novels than at the table, where there is always the incentive to try to flee all together as the DM won't be so mean as to kill us as we admitted defeat... won't he? (puppy eyes). With a doomed character, you're effectively dead, it's too late, but you get the opportunity to shine. I really like it. It's a strong contender for my answer to the thing I prefer in LU. [That and it's linked to a waaaay underplayed tool in O5E, exhaustion levels, that I have houseruled to extrapolate... "you're visiting the plane of the dead... breaking the rules of the dead will make you lose the will to get back among the living..." ]