Leaving a career in clinical medicine is often a one-way path. There are ways to return to clinical medicine after you leave, but it can be difficult (and costly). I often spend quite a bit of time speaking with people about this critical question because although the grass may look greener on the other side, that may not be the case.
As the health care system evolves, you may consider pursuing a non-clinical career. Remember that you may have the option of a blended career where you spend a part of your time in the clinical space (perhaps moonlighting or working an occasional weekend shift in the ER), or you may wish to transition to a part-time schedule and fill the rest of your time with some writing, blogging, consulting, teaching/tutoring, etc. There are ways to keep your feet in both the clinical and the non-clinical worlds of medicine and if you choose to make a slow transition, this is often an easier way to make that switch.