User blog comment:Mich, Michele & Kuhla/Future Units Preview/@comment-26917552-20151205182203/@comment-27109417-20151206043243

As cool as that may sound, it ain't so easy. Since Alim was never part of the creation of SAO, they do not have the permission to add SAO content into their games. The only way they could add SAO content would be to do a collaboration with the creators of SAO, in which they would need their permission first. They would need to go through some liscencing issues as well. After doing so, they must both decide what SAO content can be added into Brave Frontier and what Brave Frontier content can be added into SAO.

Therefore, it is POSSIBLE, but it would be really difficult and troubling to make it work.