Miranda v. Arizona was decided over 50 years ago. How relevant is the behavior of SCOTUS 50 years ago to predicting their present-day behavior? The membership is completely different, and there have been countless other changes in law and American society and culture over that period. (I'm not necessarily disagreeing with your point, which may well be right, but your example might not be the best example to demonstrate it.)
(And especially considering that the present-day SCOTUS has been accused of repeatedly eroding Miranda v. Arizona, see especially Berghuis v. Thompkins in 2010.)