The UGL case is still to be investigated so he could go down. Although he definitely has no intention to step down unless the central government forces him to. Its a good interim solution to alleviate the tension, I think the students will take this as a good gesture from mainland and at least go home for the moment....who wants to stay out on the streets indefinitely? Everyone is looking for a mutually acceptable solution.
Carrie Lam would be a good replacement, at least she has much more credibility. It seems that both sides respect her in some regards, since she has the capacity and seems more genuine.