TC has announced to complete ICS updates for all announced devices by the end of August. By giving the answer of a fan about Ice Cream Sandwich update for Thunderbolt on Facebook page, HTC said that “The Thunderbolt is still set to receive ICS. We’re still planning to finish updates for all announced devices by the end of August. Thanks for remaining so patient!”
Keep remember that this statement doesn’t mean that you may get Ice Cream Sandwich update by the end of August, because you mobile carriers will also test the updates, which takes months to complete. So according to HTC, be patient!
source: HTC (Facebook)