PokeBank simply activates Pokemon Link, because it uses this system for special distributions, like the Celebi. Since OR/AS would be using this same feature, Pokemon Link will be usable, as it is independant of the PokeBank.
For those who don't have PokeBank and did not unlock Pokemon Link, they can most probably unlock it when they transfer their first Pokemon from OR/AS to X/Y.
NOTE: It's highly likely that during the demo plays of OR/AS, Pokemon Link will not be usable.
Hope I helped!