It looks like Sense 3.5 is/will be released on the newest, and future, HTC single core phones. (There are custom ROMS for the Desire S with Sense 3.5 already.)
And recently there was a leak from HTC of a beta ROM (for the Desire S) running Android 2.3.5 and Sense 3.0.
So it looks hopeful that there will be an update to Sense but, as to which version, no one can say with certainty what HTC will do.
