(And considering how he doesn't quite seem to fit in anymore, ever since his return, I don't think it'll take long) there should be plenty of space for everything to happen. If you think about it, the king killing will be just a single episode of his life, like the one with the Maer. And the Maer was actually three episodes, first in the city, then in the forest with the bandits, then with Felurian. And that only took about half the book or so!

In other words, when Rothfuss is out to actually get things done instead of fleshing out the details of Kvothe's life, he accomplishes things quite quickly. Of course, given the sheer number of years still left for Kvothe's story to cover, I have no doubt we'll eventually reach a point where Kvothe just wanders off searching for rumors of the Chandrian, or goes back to finish training with the Adem, or some other similar timesink. But When that happens it'll seem natural, like Kvothe's decision to not bother Chronicler and his future readers with the details of his trial.

And if I speculate even further, it is entirely possible that Kvothe misjudged how long his story will take, or got bogged down in details and pleasant memories, etc, and thus runs out of time and is forced to leave the tale unfinished. It is not impossible... And we'll be left uncertain whether or not it was Rothfuss's plan for Kvothe all along, or if Kvothe is merely covering for Rothfuss.

In other news, I was apparently alone in not knowing that there is going to be a second trilogy, but it is awesome news.