I can't remember if Todd said anything about how long the main questline will be, does anyone happen to know? The MQ in Oblivion was ridiculously short IMO. I've only played a little bit of Morrowind as a kid so I don't really remember a whole lot about it or how long the MQ was.

30 hours, confirmed in several interviews

i haven't completed the main quests of Oblivion or Morrowind, but I'm told they were both around 15 hours or so