I believe that the first season was like setting up Clem to learn to make the right choices and how a random stranger you meet could become so impactful, the second season was like Clem using what she learned to make decisions for herself, and I think that the third season should be that she is older, and all the previous decisions you made before represent who she ultimately becomes.
I also think this is how the third season should go. Then if Telltale wants to do something new this would also be a good time to end Clem's story, not necessarily kill her off. But just wrap up her story. Seeing who she ultimately becomes would be nice closure and a good finale.
Also the Clem Trilogy sounds cool.