It's not clear what will be airing on the 8:30 timeslot next week. Stay tuned to the TV Ratings Guide for more updates.
Update: No press release has been released yet, but there is no doubt that Powerless was canceled and pulled from the schedule.
Update #2: Per a source, "NBC emailed a schedule change yesterday noting which Powerless episodes would be on April 6 & 13, the website may just not have caught up." Still no press release. Powerless was not pulled as of yet. But it's still certain to be canceled.