First of all, if by chance we acquire RGIII, it will certainly say that EJ is done in Buffalo. But given RGIII's quals, his draft status and his rookie year performance, a healthy (mentally and physically) would be far better than EJ.
Your second point is well taken but I really don't see how Hackett survives this off-season. IMO, he is gone for sure and Marrone by association. Or by defiance of Whaley.