H50 was renewed a while ago.
There is a really bad guy loose now because Chin let him escape. THAT will have far-reaching repercussions. I think he chose his wife, because the bad guy said that Kono was on a boat, so he banked on them throwing her overboard. She is a very good swimmer, and will likely be able to survive. I know it LOOKS like she's drowning, but I think she is waiting for the killer to leave before she comes to the surface.
They sure didn't have a long plot about the killer of the police chief, and bomber of the police station. McGarrett made short work of her. Wouldn't stopping so many bullets have given him some serious non lethal inguries? Maybe not with McGarrett.