Kasumi's departure (oh I have to go back to my gym BYE), look at Shigeru's departure (I'm going to be a scientist for no adequately explored reason!), look at Takeshi's departure (I'm going to study to do this job that was made up one episode ago!)...most of the goodbyes in this show have this horrible, slapped-together-at-the-last-minute vibe to them.
I wouldn't be surprised of the Rocket trio got the same treatment, especially considering how crappy the writers have been to them this series. Everyone expects there to be this huge epic showdown between Satoshi and Sakaki and for the whole "Rocket-Dan gets disbanded" thing to become this major story arc, but the truth of the matter is that the precedence isn't really there. I expect a two-parter at most.