The smartphone maker announced back in February that the device would see Ice Cream Sandwich, however it has yet to clarify exactly when it will do so.
Tech site Pocket-lint, which was unable to confirm the news from HTC, claims that Canadian carrier Telus confided the cancellation is a result of poor performance during the testing phase. It's not a common practice for a handset maker to cease development of an update, especially one as major as Android 4.0. Typically, companies will only list devices if they feel strongly that such an update is possible. However, as we've seen in other cases, things can change quickly if the device doesn't perform to standards.
This isn't exactly the end of the road for ICS on the Desire HD, since it's possible for the phone to pick up the update in a less official capacity. Rooting and flashing a handset with CyanogenMod has become a common practice among adventurous Android users, and the Desire HD could perform better with this ROM than running HTC's Sense UI-laden build.
It's still murky as to whether HTC will try to release a stripped-down version of Android 4.0 for the Desire HD. You may recall a similar situation last summer when HTC stated the original Desire would not see 2.3 Gingerbread only to later say that a modified version of Android 2.3 would indeed eventually arrive.