yeah, probably someday that will be the case but not now, its not really needed.
Also, I don't know of any cable co's that are truly using GHz of bandwidth. The one I work for has all 1GHz equipment but still run at 860. I think the reasoning behind it is signal attenuation as you reach that 1GHz range over drops and in home cable that will begin to be a headache. If they can get away with 860 and use SDV id think it would be a bit more reliable and easier to keep customers in specs. Not to mention once all of the cable co's drop analog, thats a LOT of bandwidth that will be available.