They're not creating a federal licence, but enhancing current state licences to meet the federal government new rules so Uncle Sam could accept them as ID. Everyone would have to get one. The idea of a federal licence will make the states go apeshit because it's a state right.
Basically... If your licence has all of these: "Each card must include, at a minimum, the person's full legal name, signature, date of birth, gender, driver's license or identification card number. It also includes a photograph of the person's face and the address of principal residence"; your licence is already RealID and you're forever stuck with that photo for the next four years.
However, the Congress may amend or repeal that law. It's all on the Wiki.
And licences that let you cross the border are different from normal licence (just more enhanced). They will be still issued by the states if they offer such thing. The federal government already offers passcards for this purpose.