Gotrek won't meet his doom in Kinslayer - there is a book coming out after it simply called 'Slayer' which has a cover showing Belakor in the background and Gotrek & Felix in the foreground with a daemon head in hands.
Seems to me like they will go North to fight Throgg and his army of trolls. Defeat Throgg, or survive him - although a few of the favoured party are meant to die in the battle - and then will head North to find Gotrek's true doom somewhere in the wastes against Belakor himself.
Considering heroes without models are being killed off I think we're going to see either Felix die and Gotrek wander off with no-one to record his doom, or Gotrek die followed shortly after by Felix.