Yes, I agree (and said so already) that the CDC may very well change their recommendation and the WHO sets their age older already.
As far as I know the major theme park companies (Disney, Universal, Sea World, Busch Gardens, Six Flags) all have the same policy around age for masks as well as the major airlines. In the Orlando market I know LEGOLAND has no mask requirement. All those companies are falling back on CDC and public health official guidelines and it’s my opinion that if/when the CDC revises their guidelines than most if not all of these companies will update their policies. Is it possible that Disney or others will change the policy before the CDC moves on it, yes sure, but IMHO its not very likely.