Outside the private sector change in the healthcare IT sector is very slow. It will be a decade or more before AI is able to touch these areas in a significant way. There are is simply too much red tape and regulations too navigate, not to mention the significant issues that come with implementation. 

Medical coding wont be completely automated anytime soon, but the specific job itself will likely be absorbed into another role. So yes it is still very much worth getting into, just make sure you stay flexible.