Will the expansion, 3.0. Replace the mainstory quests with new ones and Reduce the 2.0 storyline to backstory like ARR did with 1.0, or will it work like the post-ARR patches (New level 50 quests that start when the last story quests left off)

Related, will there be servers that allows players to play at least part of 2.0 when the expansion hits?