Every block of Magic really has two storylines: The short-term one and the long-term one. The former means the local conflicts on whatver plane is under consideration (the breakdown of the Guildpact, the disappearance of Avacyn, or what have you) and is supposed to be resolved in some form by block's end. The latter is really the story of the planeswalkers and whatever loose ends are on the plane - who survived the Eldrazi devastation? How is Ravnica being run now that Jace is the arbiter of all things? And will Liliana be able to kill all her Demon-masters, or will Nicol Bolas conquer more worlds? That part is really, really long-term; it's been twice as long since the Lorwyn Five planeswalkers were introduced than the entire Weatherlight Saga took to play out. Very few people know all the endings - but storyline writer Doug Beyer does.
When zeritanos asked Beyer on his Tumblr blog, "Can we at least get an idea of if/when certain story points will see closure, if at all? Such as Karn vs the Phyrexians, Gideon vs the Eldrazi, and Elspeth vs the Underworld?" he replied:
Many storylines have closure planned on a long time horizon. For some values of "long." More specific than that I cannot get, yes, mmm. I like closure. Magic's storylines can sometimes take awhile though.
This means, happily, that we are avoid "Lost" syndrome: lots of cool ideas being thrown out with no one having any plans or idea of how to see them out to their conclusion. So far Venser is the only new-style planeswalker whose story has "truly ended" - but more will probably be written to a conclusion.