I don't think class change should be implemented and they'll never do it.
Why won't they ever implement it? Easy. They can make more money if you create more chars bec you want another class and you'd probably buy slots expansions. Also think of the wep, they'd have to make a system too to change the wep to your new class. On the other hand, if you just change sex or race, it's just a appearance alter in deep, which shouldn't have been hard for them to implement since it's just modifying a bit the appearance alter voucher behavior and make a new item out of it. And I don't think