Didn't they already get back together on a tour a few years back for a tour? I kind of doubt they'll record another album. Ihsahn and Sammoth are just at such different places musically. At the same time, it wouldn't be the most shocking thing in the world.
Im sure i read somewhere that Ihsahn said a new Emperor isnt impossible in the future. When he gets tired of his solo project he might go back to Emperor or something. If they went back to it now it would just sound like his solo project.