Isn't standing on a bridge while burning it down EXACTLY what Sylvanas did with the Horde in BFA? The only difference is that when Tyrande destroyed the ground she was standing on she actually achieved what she intended to achieve...while Sylvanas lost the Horde out of sheer stupidity.
OT:
In a fair fight using only the powers we have seen so far Tyrande would stomp Sylvanas into the ground without breaking a sweat. But this is not the way such duels actually play out in WoW. Malfurion was not just "slightly" stronger than Sylvanas when they fought...he was WAY stronger. He had been fighting for days at that point, holding up giant walls of whisps and mass-rooting entire armies...while Sylvanas chilled in the background and ambushed him. And she still lost very clearly. Yet, the devs wanted him to lose, so he lost.
If Tyrande and Sylvanas ever fight each other the one the devs want to lose will lose. And the devs ALWAYS want the Night Elves to lose. So the answer is extremely obvious.