I doubt seriously that the Eagles will trade Wentz under any circumstances. He is viewed as their long-term franchise QB, at least at the moment.
I would not be surprised if Foles chooses to stay in his role as back-up, but after his performance during the playoffs, he may well be a sought-after commodity as a starter for another team. However, part of his success on the Eagles is/was likely due to his offensive line's ability to protect him and give him time to survey the field and then make the correct decision. Without that protection, and being rushed in the decision-making process, he could go back to performing as an average NFL QB.
I don't think Carson Wentz is going anywhere. He is young and has already shown promise as having the skills and intelligence to be one of the league's top-tier QB's. Of course, as we have seen with other QB's, injuries can really impact a player, both physically and mentally.