I know someone will probably ask why then can we fly them to ATH from PHL. The answer is that the ATH flights are planned with severe weight restrictions as a trade-off to not serving Athens at all and essentially giving it to CO. Severe weight restricting the 767 to HNL (resulting in less passengers than the 757) would surely be a receipe for failure of the route. You'll also note, US is smart enough not to attempt the flight in Winter. I do not know if Parker has decided to pay Boeing to increase the 767 range capability, which is an option they were considering. I doubt it though, unless someone here knows more about this.