To salty Allies (like the guy who can't spell to save his life above me) - the tree burning has SO LITTLE to do with the faction war, it's silly.
Yes, the Horde will Burn it = and yes, the alliance will trash Undercity. That's an equal event. The alliance will not be able to use Undercity, the Horde will not be able to use Teldrassil. Again, that's an equal event. (and set up that way so that low level players can still enter those areas and make some use of them via phasing)
But the tree burning is part of a MUCH BIGGER situation. One that is likely going to result in the Hour of TWilight - and at this point, THAT should be looked at as a POSITIVE.
There's been five world trees after the original was destroyed - all planted by Staghelm (remember him?) and they've all died/been corrupted by the nightmare/halfway ripped out of the ground, or chopped down.
...Teldrassil was the last one.
When it's gone, bad things are going to happen...where they would not if you still had your stupid tree. Those bad things are going to save this expansion from being pure filler. Thank GOODNESS, because it doesn't have much of a leg to stand on right now.
Can you relax a little about it? It's all for the good of the plot.
Likewise, we know that Saurfang and Sylvannas will live, and YES, we have no idea if Malfurion will. Do I think that Malfurion could kill Sylvannas? I think he could if it were a fair fight - or even a moderately unfair one. But Sylvannnas is NOT SOMEONE WHO FIGHTS FAIR. She's going to do something. It's going to be VERY bad. And naturally, with no true archdruid to grow a world tree at an insane rate (no, your "archdruid" player character is NOT on Malfurion or Staghelm's level), what the world trees are preventing...is going to come to pass.
"Five torches to light our way".
It's going to be BAD.
And awesome. And drop epic loots.