Earlier this week, CNN asked me to write an op-ed on Ted Cruz, and whether he’s a realistic contender for the presidency. My reaction: Of course he is — but probably not in 2016. And for that matter, neither are the Republicans who seem to get the most mention for that position: No one doubts that Cruz has a bright future in the Republican Party, but that doesn’t mean the future is now.Cruz, like Rubio and Rand Paul, have only barely arrived on the national stage and are many years younger than their sell-by date. None of the three has...