At least in the US....was this not b/c the big manufactureres did not get behind th 18HTs?
Basically, PC and H set the trend in the US for beachcats. I bet F16 would not see as much growth were it not for Vectorworks building the Blade. What if PC offered the 5.0 with F16 rigs. That would be interesting.
The only way the F18 will use SlimFast is if PC and H see economic incentive. At this point there is not economic incentive to make a change to the rules. It would take half the F18 fleet dumping their boats and go somewhere else (not going to happen) for any changes. They cannot afford to alienate their current sailors.
The only other current day problem F18 has is class division. What if H forbids PC in their H regattas and PC forbids any changes to their platform (sail maker, hardware, etc.) and mutually creates a divide in the F18 fleet? F18s are here to stay (as is) until PC and H decide differently.