"49er grew with Olympic selection"
Well, the class wasn't launched before it was selected; but are there many places where it is the most popular skiff type? I know of nowhere that has other skiff types where the 9er is the most popular, despite its strengths.
"Laser is definitely growing at the moment"
Yes, but in one of its biggest, strongest areas (at least) that growth has been in kids, women and Masters, and the number of men in the "Olympic" age group has dropped; last time I checked, the 18-35 had gone from 75% to 25% of the 'big rig" fleet, and the big rig fleet itself has dropped. And the Laser had massive fleets before it went Olympic; much bigger than any board class has these days.
"I would guess including the radial rig version - both olympic specific developments from existing fleets; without olympics neither would exist."
Sorry, that's wrong. The 49er was NOT designed for the Olympics. The Radial was NOT designed for the Olympics. I've interviewed 3 of the 5 figures involved in the 49er's conception (Frank, Julian, Peter J but not Dave O or Otani), and all three of those who created the Laser and Radial (Hans, Bruce K, Ian B) about the conception of the classes.
IMCO is interesting. Sure, it may have helped keep longboards going, although D2 died when the Lechner was selected.
On the other hand, at the end of the IMCO's Olympic days, there were only two (limited) production longboards in the world. The IMCO ended its Olympics in 2004; in 2005, the Kona One started the regrowth and now there's about a dozen longboards with centreboards in production. The fact that the regrowth started straight after the IMCO got dumped may indicate that the IMCO may not have kept longboards alive.
BTW we can produce new boards but can we produce classes that quickly?
I'm not saying the above conclusions are necessarily accurate (at least some of the facts definitely are) but shouldn't this stuff be put up for consideration?