You haven't mentioned the kind of commitment you have to theatre/ music interests other than 'high intensity'. I am not involved in these activities, so it is difficult to provide insight.
I am aware of students that spend a lot of time pursuing sports, small business ventures outside medical school and recently spoke with students who are part of the university orchestra (they mentioned this was a considerable time commitment). These are medical students from 1st to final year, which suggests that you will not have to completely abandon your other interests. Personally, I have worked throughout medical school, committing to 35 hours per week in my 4th year. As with all things, you may have to compromise. Its up to you whether you would like to be a high achiever/just pass or give up some of time you spend pursuing outside interests. You may feel especially pressed for time around exams.