Personally I wouldn't be too keen for Lars Eric Si to take over vocal duties for Arcturus. The guy can sing, there's no doubt about that, but on the Winds album it just seems like the vocals are there just for the sake of it, to sound pretty, and he doesn't seem very adventurous. Garm has a certain quirkiness and grandeur (not just with his vocals, but as a person too) and that was absolutely perfect for Arcturus. He'd be a hard guy to replace.