HTC Desire HD will not get any Android 4.0 update and this seems to be final.The reason given by HTC is that the device shows poor performance while on Android 4.0.HTC Desire HD was best suited for the current software it is carrying.
HTC did apologize for the confusion caused to the customers thinking HTC Desire HD might get Android 4.0 update.
“After extensive testing, HTC has determined that the current version of HTC Sense with Android provides customers with the best experience on the HTC Desire HD. When we consider new versions of software, we weigh a number of factors, but ultimately the customer experience on the product is the deciding factor. We apologize for any confusion this change may have caused our customers.”-HTC