I play Demo spec, and looking through my talents, everything that procs off of Shadowbolt also procs off of Incinerate. My cast time for Incinerate is actually faster than Shadowbolt, and (I'm not completely sure here) but I think that it does more damage than Shadowbolt as well, especially when Molten Core procs.
The only reason I hung on to Shadowbolt was for Shadow and Flame, but now that's not an issue anymore. So is there really any reason to use it? Or am I missing something?