HTC One M7 and One M8 owners are out of luck and will be stuck on its current version of Android for life. The One M7 was released in 2013 and the One M8 followed up in 2014.
HTC announced on Twitter that it will bring Android N, which Google is leaving the naming to its users, to the HTC 10, HTC One A9 and the HTC One M9.
During Google I/O, Dave Burke, vice president of engineering at Google, stated the next version of Android (possibly Android OS 7.0) will officially be available later this summer.
Related: HTC 10 review: Back to basics