Hello Lain59,
Is this situation so bad that perhaps you should take him to your local emergency room? Also, I would not wait so many days for the doctor to call back. Does he or she have an administrative assistant who can page him/her?
And, the answer to your question, is YES he can get better but he needs appropriate and quality care. If, he is asking to go the ER/Hospital, I would take him ASAP because psychosis can be very scary for the person.
Today, there are wonderful medications for psychosis and new ones are being developed on a consistent basis. There is hope... I know people with psychotic disorders with college degrees that work full-time so please don't think that your child's future is wasted. There may be more bumps in the road but if you get him the proper assistance he should improve.
Best of luck to you...
Rox