Is it just me, or does everybody want to see Tsunade dead? She is the best female medical ninja there is, and with her techniques, she should be able to heal just about everything. And the other Kages aren't that hurt:
A/Raikage: one stab wound
Onoki/Tsuchikage: blunt force trauma
Gaara: stab wound
Mei Tesumi/Mizukage: blunt force trauma
We have seen worse! So I agree, it's rather something symbolic to see her body crushed by a Mokuton-technique. What may be possible is that her time as Hokage are over. But she certainly won't die.
And the story line wouldn't add up. Dan saved her and ordered her not to follow him in the near future (http://www.mangapanda.com/naruto/591/14). It would be strange if she survived one attack just to die 10 minutes later.