Fairly sure sylvanas still has over 2 left after the one that has died. Also, 1 valkyr for over then thousand innocent lives?
Well, it does not say it exactly like I did, however it mentions that in the rest of azeroth there were far too few night elves compared to those that perished in Teldrassil
When I did the horde questline, you had the choice between killing or sparing some civilians. When I did it on alliance though, it said that all were killed, not even civilians were spared.
" The World Tree was more than a city. It was an entire land, home to countless innocents. How many night elves were elsewhere in Azeroth? Far too few. Now, they were all who remained of their people."