On HTC Facebook page, they have just confirmed that the HTC One X, One X+, One S and Butterfly will be getting Sense 5 (aka ‘New Sense’). They haven’t said what features from Sense 5 will be coming to these handsets, but have noted that any thing on the HTC One that requires the Ones updated hardware will not be available on the older handsets, which makes sense (no pun intended)
As for timings, well, who knows. I’m guessing they’ll want the HTC One out there for a few months before offering it’s features to existing handsets.
As soon as we hear any more, you’ll know about it!