The Android Phone Fans site has posted HTC's second and more detailed statement about upgrading its existing phones to the 4.0 "Ice Cream Sandwich" version of Android. It's a little more specific and expectation-raising than their initial "we're studying it" response.
Upgrades require a careful balance of hardware and software to ensure the best possible performance and usability, so please stay tuned as we assess our product portfolio. Our goal is to upgrade as many HTC devices as possible and we’ll be sharing details on specific devices and timing in the coming weeks!”
-Phandroid, October 21, 2011