Just my guess here, but, I think Bushmaster is in the same boat as most other AR manufacturers. The pontential is definitely there, but, there will have to be enough interest to make it cost effective to do. Fortunately, there arent a lot fo changes to be done to make a 6.8 rifle vs. a 5.56. The changes that do need to be made, are all in the upper receiver, so it sholdnt be a huge deal. However, demand and interest wont be there until ammo and mags are readily available. As soon as ammo is easily obtained, and mags are shipping, then we'll be able to see what demand will be like.
The ban going away in Sept. will also go a LONG way, as it will allow high cap mags to be readily made and sold again. I can see Bushmaster (as well as other makers) putting out a 6.8......eventually. Personally, a 6.8 with a 16-18 inch chrome lined barrel would just make me all warm and fuzzy.