I think this is a difficult thing to predict. First, there is no evidence that executive functioning skills should be anything other than age appropriate regardless of IQ, there is no research that indicated that the two are correlated. Secondly, EF continues to develop well in to the twenties, as many of these skills deal with frontal lobe development. So unless you are comparing EF skills in the late twenties it is a pointless endeavor. Also, people often think of motivation as EF, maybe it is and maybe it is not, but a parent wanting a child to do something is not the same as a child wanting it themselves;).