The whole line will be eventually changing over to the EVO style grips I would imagine. I think that's a great idea since we haven't had an obvious upgrade to SAK styling in many years- The last major overhaul was in the 60's when they started "hiding" the rivets and then shortly afterwards removed the bail.
As for why there's no OH blade available on a variety of models, well my contact at Wenger hasn't even gotten his hands on one of the OH models yet, so he can't answer that!
I imagine it will just be a matter of time.
Def