imo walt jr will die, but not of a car crash. he'll off himself imo and that could be the final scene in the last ep before break. he seems real depressed and uncertain about what is happening. would be pretty full on really.
I think the car crash is coming and I think it will be Skyler that kills herself as a result. She's giving that sort of vibe, she's already off the rails completely and the kids are all she cares about, Walt Jr. dying would just push her over the edge, hard to see a role for her after that. My guess is she'll out Walt with a note, kill herself - Leaving a huge mess with Mike after Walt, Walt still in the meth game and his INFANT DAUGHTER in the custody of the people trying to catch him.