Here is a roadmap on Lollipop for HTC smartphones

If you happen to own any of the mainstream and budget handsets from HTC, then you would require a lot of patience. HTC will definitely be rolling out Android Lollipop updates for your handsets, albeit slowly. According to a report on a Vietnamese website, HTC has plans for rolling out the Lollipop for their devices during the year, but will do it at a snail’s pace.  

HTC has planned to update the HTC One M8 and HTC One M7 in the first month of 2015. HTC One E8, HTC Desire EYE, HTC One M8 EYE and the HTC Butterfly 2 will receive the update in February. March 2015 will see HTC One Max, HTC M7 Dual SIM, HTC Desire 816, HTC One Mini and the HTC Desire 820u getting the Lollipop, while HTC Desire 610, HTC Desire 510 and HTC One Mini will see it only by April-May 2015.

However, the information is not official and was leaked out by the Vietnamese website HTC-Vietnam.