Not sure how it works where you live, but here we have re-orientation programmes for psych nurses who want a change. They work 3 months in medical and surgical wards and the expectation is pretty much that of a new graduate nurse. It really depends on the stigma at the hospital or place of work. Many of my colleagues have gone on to other fields such as ED and ICU, Medical, Paediatrics, Public Health Nursing (common) or Health Promotion. I worried about the same thing, but I've had a lot of diversity and challenges in specialising in different areas.