The only real way to protect the one-design status of any class is to have it recognized as an International Class by ISAF. There are some significant hurdles to overcome (like having worldwide distribution), but once recognized, the class is protected from significant unilateral changes by the manufacturer.

The major Hobie classes (14, 16, 17, 18) are all International Classes. As an example of how difficult it is to make "significant" changes, it has taken over 3 years to approve the new outhaul and downhaul systems on the 14 and 16.