So, the big question/secret tying us to the next season, (however long we have to wait for it), is: What did Jenner say into Rick's ear at the end? Maybe Rick's wife, Lori, is pregnant? (Her illness/vomiting). Jenner found something in Rick's blood that could be a key? I think it was that Andrea has the virus, (hence the bandage and her wish to remain at the CDC and die painlessly).
However, during an interview with actor Noah Emmerich, (Dr. Jenner), he said the following:
Q: So fess up. What did Jenner whisper into Rick's ear?
A: "You know the most important thing to remember in life, like the most important thing in life? If I could tell you one thing that's the most import thing to get by and have a happy life, it's that -- [Emmerich begins mumbling] -- and that's exactly what it is." Did you hear me?
Any guesses?