HTC has said that it is already planning on bringing the new Android OS, Android L, to the HTC One family including the M8 and the M7:
"HTC is excited about the new features in Android L and we can't wait to share them with our customers. We are committed to updating our flagship HTC One family as fast as possible. We will begin rolling out updates to the HTC One (M8) and HTC One (M7) in regions worldwide within 90 days of receiving final software from Google, followed shortly thereafter by other One family members and select devices."
The news is likely to be welcomed by HTC owners, although it's worth noting that while HTC is going to be working as hard as it can to bring the update to its users, Google has yet to announce when it plans to launch Android L to the general public.
Still with an Autumn release schedule that should mean Android L on the HTC One by Christmas.
The announcement ties in with HTC's Advantage scheme, previously outlining that upgrade aim to encourage Android fans to stick to HTC. HTC delivered, just about, on the KitKat upgrade, although using a phased roll-out means that it won't be 90 days for all users globally.