Until they get the MPEG-4 STB replacements all straightened out they are really tight on space and will have trouble adding new HD channels. Even then I doubt HLN HD would be in the first group to add as they probably would want to add Mpeg-4 channels and will have not replaced all the stb for those who get HLN in SD.
It is one of the channels that verizon will be adding in the next few months once they settle their other tv issues. Right now channel 601 is currently being occupied by yet another one of those upgrade to fios quantam promotional spots that are spread out all over the guide. HLN used to be known as a headline news network.