So the obvious feud is Big Show vs. Tommy Dreamer for the next few weeks.
Heyman's heel turn actually makes perfect sense considering he's been telling Rob for WEEKS not to defend the title so damn much. In kayfabe, he'd rather have an ECW Champion that won't risk injury every week. The fact that it's his old protege Big Show is the icing on the cake.
Quite frankly, I think this is the best thing to happen to ECW since its rebirth. RVD gets to recharge, gets a megapush as a plucky babyface upon his return, and ECW actually has an intra-ECW storyline (Big Show as heel champ ruining people) that provides opportunities for the directionless guys (Dreamer, Sandman, etc.)