I love Daryl Dixon. I don't love the fan pandering they've done with Daryl Dixon.
I think that Daryl SHOULD die to serve the story. He's already a hero. He doesn't need to die heroically to prove that yet again. I think that he should die in some totally brutal and pointless way, such as getting the Lucille treatment or getting some realistic illness. I think seeing Daryl "Superman" Dixon felled by something and wanting to fight but not having any way TO fight would be truly tragic and heartbreaking to watch.
However, I don't think AMC is going to mess with their money. The show is a business. Daryl is the biggest part of that business. At least for now.
The one thing that may endanger Daryl's life is the Frank Darabont lawsuit. If his lawsuit is successful or may even look to be successful, I could see AMC killing off Daryl as a way not to have to pay more money to Darabont. I'm not too familiar with the details of that lawsuit, but I think that part of it has to do with money earned after Darabont's departure based on his creative input into the show, which would include the Daryl Dixon character. If that's the case, then I could see AMC being vindictive and petty about it despite how much they're earning from the show (even if they had to pay Darabont more). However, the whole Darabont lawsuit may just be based on episodes and not other marketing, so then the Daryl Dixon character wouldn't be an issue at all.