Some children are left-handed, but are forced to become right-handed. This forcing sometimes leads to the child having speech problems. It is better to let his natural inclination prevail. But I agree with you that its a right-handed world!
Desks and books are designed for people who are right handed. But your son will make the adjustments as he grows up. If he could copy a pattern to perfection (even though laterally inverted) he seems very talented. Just tell the teachers that he has problems with copying from the board. Surely they will have some methods of coping with diversity in children's functioning.