I don't feel like Tirion has to die for us to be able to obtain Ashbringer... perhaps he simply passes it onto us (the player) after we do some super-heroic deed. I can imagine some kind of scenario where a very rare (legendary...) drop, combined with an epic quest chain could result in somehow impressing Tirion into giving you the Ashbringer -- I don't know how much that would fit into Blizzard's idea of everyone getting to experience all of the cool storyline stuff as very few people would get to experience whatever quest chain they put together for that, but I had to think of some way that Tirion could survive and still put the Ashbringer in my hands. Plus phasing could make it so any player with Ashbringer would see Tirion wielding some other weapon.

And the debate rages as to whether we'll be able to obtain Frostmourne... I'm sure we will, and for a long time I thought that was kind of dumb because of the lore and power surrounding the sword (how are we able to escape its call?) but thinking about it... the only way we're going to get it is if we defeat Arthas, which means we'd *probably* be killing Ner'zhul as well, and it's his spirit infused in the sword, so when he's dead, Frostmourne probably loses a lot of the power we associate it with. However... I can imagine an angle Blizzard could take where in the Arthas fight we somehow expel Ner'zhul from Arthas' soul, saving Arthas -- and setting up an encounter against Ner'zhul in a Sunwell-esque (expansion timeline wise) final raid of WotLK. If that's the case... another epic question to break Frostmourne of the Lich King's power could explain the player's ability to wield it. I can imagine some kind of epic, heavily phased quest line to save your own soul and refuse the call of the Lich King.