I think we are going to see Kier on-screen in the next season; and I believe it will be played by Sean Penn.
I realized upon a rewatch of "The Secret Life of Walter Mitty" that Ben Stiller has re-used the pilot as Mr. Drummond. Obviously, Adam Scott is also featured in this movie (albeit, as an antagonist).
His reverence towards the actor in giving him such a role leads me to believe that not only would the casting be appropriate, it could also could be meaningful.
Even better would be if first we see Crispin Glover "as Kier" being paid to portray Kier, only to reveal a holographic image of Chris Penn talking about Crispin being payed to play Kier while having a wax figure carved of himself; to then finally reveal Sean Penn apologizing for the inaccurate portrayals of himself, the real Kier Eagan.