There are only 3 players I would trade Calvin Johnson for straight up in a dynasty. ADP, MJD, and Fitz. I'd call Calvin and Andre a wash, and I probably wouldn't make that trade from either side (Andre for Calvin *OR* Calvin for Andre) because at that point it's trading just for the sake of trading.
If I owned Calvin and someone wanted to get him from me, I would require a multi-player deal that contained *AT LEAST* one of the following players: Chris Johnson, Knowshon Moreno, Reggie Wayne, Steve Smith South, Roddy White, Vincent Jackson, Drew Brees. In addition, the deal would have to include at least one other high-quality fantasy starter. There are other fantastic dynasty players that I absolutely love (SJax, Gore, Moss, etc), but I wouldn't trade Calvin for an offer featuring one of those guys as a centerpiece because Calvin's window is just so much larger than theirs. I'd need a high-quality dynasty stud with at least 5 years left in the tank just to open negotiations.