Ray is undoubtably the star of this show, but losing Mickey it would be a non sense.
Every star needs an opposite, and Mickey is the one. Above all, Liev Schreiber is a great actor but Jon Voight performance in this series is a great gig.
Ray hates and loves his father with the same intensity. He is the only one of the 4 boys who deeply mourns him. He wasn't prepared for this loss.
Last scene shows that he cannot accept being foolished (once again) by his own father.
Please authors, don't let Mickey go.