If we assume determinism to be true, whatever answers you arrive at to this question were the ones you were always going to arrive at.
My current view is that if you are capable of concerning yourself about the impacts of a belief in determinism on ethics, you are very likely to be the kind of agent who will at various times continue to feel like there are moments in your life where you have to choose between what seems to be right and wrong, regardless of whether you develop a belief in the reality of determinism or not.
Given this probability, it seems likely that you will be drawn to take seriously some kind of ethical framework or other. Perhaps a conviction in determinism will in fact crystallise rather than undermine your commitment to a particular ethical framework.
I regard this as an extremely interesting but potentially intractable issue. I know I want answers and certainty in my life, and it is possible a belief in ethics will bring more certainty than otherwise, especially if I come to believe that this belief in ethics was in itself determined.