HTC recently updated its Android 4.0 delivery schedule for its devices. In addition, the upgrade to Ice Cream Sandwich will include HTC Sense 3.6. Below is the target timeline for the HTC devices:
Users should take note that these dates are targets and may change due to localization, testing and partner approvals. According to HTC, rollouts can take up to 45 days from the initial update to reach everyone.
The HTC devices that are not getting Android 4.0 update include the Facebook phones HTC ChaCha and Salsa, Wildfire S, Explorer and HTC Flyer. However, HTC states that these devices will continue to get software improvements, security fixes and technical support.
HTC Sense 4, which debut with the unveiling of the HTC One, will not be included in the Android 4.0 update as certain aspects of the Sense 4 require dedicated hardware, which is not available on all devices.
Source: HTC Help Center