If Rigsby and Van Pelt are going to be written off the show, they will, most likely, be killed a RJ disciple. This will cause the CBI team (Jane, Lisbon, Cho) to be angry like crazy, and they will catch this RJ disciple in the season finale. As they try to catch this RJ disciple, Jane may explain everything that happened with RJ in the episodes before the finale. 

I would like it if BH shows what exactly happened with the whole RJ death this way.