Could it be that they did find the center of the maze, but William didnt know it? That when they arrive there, Dolores kills someone, maybe Logan (as she does 5 years earlier with Arnold). That at the center of the maze, the hosts can be set "free" by killing a human and freeing the hosts (all of the hosts) from a dismal existance by closing the park due to human/guest/employee death. Except when Arnold dies, Ford does a cover up. And when Logan (or someone) is killed by Delores, William "saves the park", as he makes reference to (as MiB) in the convo with Ford at the end of ep5.

Then years later William returns as MiB to search for this maze, but when he finds it, Dolores meets him there and maybe this season ends with her killing MiB there? She says she is supposed to destroy the park. And after she is set on her journey the first time, Arnold dies in what Ford describes as an accident. Maybe Ford knows what awaits MiB and this is why he is allowing MiB to lead himself to his own demise.