I do think S4 has good prospects, with Kripke wanting to focus more on the brothers relationship again and exploring the Winchester family history. I think that's the right direction. With Bela out of the picture there's also one annoying factor less for next season and they might even go back to their old cinematography. So, while I am dissappointed about the shortcomings of S3 it can't really be helped and I look forward to S4. Often a good follow up season after a weaker season manages to make it more worthwhile with hindsight! :)