I haven't seen anyone suggest her acting career could continue, simply her philanthropy work.
But that goes for any career. Any Royal bride, this close to the throne, is going to have to give up her career plain and simple. They will be expected to be royals. Likely another reason royals have trouble getting married. Not just the loss of privacy and such. But losing their own career and ambitions. It gets harder the longer they wait. Kate was in university when they began dating, and didn't seem to mind not having a career, working for her parents, to accommodate the relationship. She had no career to give up. But women in their thirties will have built careers, lives and such. How many women would want to ghee up years of education and work to cut ribbons? There is nothing hands on about what royals do. They aren't out building houses, or walking dogs at shelters, or serving at soup kitchens. They are still very much doing tours, shaking hands, attending parties. With the rare exception like Harry in Africa but that was considered private. Would someone who went through medical school be happy to give up her career, to tour a hospital and shake hands?
It is likely why you see the more educated/career brides are married to junior royals. There is the exception in Europe like maxima and Letizia and Mathilde who gave up careers, not simply jobs, to marry. But you see among non heirs, and defunct royal houses, brides who are factors, lawyers, professors, and so on. The heirs if Gloucester and Kent are married to a professor and pediatrician. The difference us these women can continue three career when they marry. They get to attend Royal events, and gave titles, but they live private lives.