Despite the improvements offers in ICS, HTC wants to continue with the HTC Sense UI offering. This means that they will take time to update all of their ICS capable handsets. While the newer devices should definitely be treating to ICS we can't yet be certain if all of them will.
The official HTC statement follows:
We are excited about the latest update for Android, Ice Cream Sandwich, and are currently reviewing its features and functionality to determine our upgrade plans. Our goal for Android updates is to give every customer an improved user experience, which means balancing each phone's unique hardware, HTC Sense experience and the Android kernel. While our goal is to upgrade as many of our recent devices as possible, we are committed to maintaining every phone's performance and usability first. Please stay tuned for more updates on specific device upgrade plans.