Rubio's exit signals the futility of trying to rebrand the Republican Party. At the same time, it demonstrates the success of the Southern Strategy and the conservative movement to label minorities as "dangerous others."
GOP leaders, it's time to step aside. You've demonstrated that you will continue to reflect the views of the old and reject the concerns of the young. Unless you start taking notice that things are changing, you will kill the only chance young conservatives have at inheriting a formidable party.
Republicans have realized that they need to reach out to younger voters, female voters, gay voters, and minorities, but the crucial point that they are still missing is that the party's value system is fundamentally at odds with all those groups.