It would depend on a few factors: 1. the amount of recovery expected from whatever medical condition caused the balance problems in the first place. 2 the state of the person as a whole including psychological state. 3. availability of medical/ physio treatment to help regain balance. And probably others reasons too. Without concrete details of why the problem came it's not easy to say whether someone will recover fully or not. Can you give more information?
regards. JM