I would like to think that OC will remain as active as it is today. Sure, it'll probably fade for a while as people try out the new CC, but I'm betting quite a few will go back to OC...at least at times.
Personally, for me, it's a crapshoot that'll depend on circumstances, but, I'm betting most of the time I'll still OC, I just won't care if my shirt/jacket covers the grips/holster of my firearm, I've heard it called "casual carry", where the carrier isn't making a particular effort to either CC or OC.
I think one of the biggest things we need to do as OCers is to remain advocates and examples of how people should behave. I've heard of trash pickups along the road while carrying, I had the pleasure of participating in a fund raiser for the Special Olympics a while back, and even the meet ups at Lizzy's/Starbucks/etc help get people used to the idea of armed individuals, and of firearms in particular...all of which helps defeat the public image that we're all psychopaths/sociopaths just waiting to shoot the first person that ticks us off.