yashsingh1/xdaforums huggingface dataset:
[One (M9) Q&A, Help & Troubleshooting] shivadow:
If i remember correctly it should be april ish? I think i remember htc saying that they would release it early 2016 but seeing as it isn't a major update they might not update it at all with N being on the horizon.
[One (M9) Q&A, Help & Troubleshooting] 5m4r7ph0n36uru:
HTC One M9 already got an M update on many a device. But there are still some carrier as sprint which didn't give the got to HTC for pushing it out to those carriers devices. In case of Sprint clearly Sprint is to blame for the still not arriving M update.
[One (M9) Q&A, Help & Troubleshooting] shivadow:
Not true. Sprint do not have to release 6.0. They could be doing a samsung and working on the 6.0.1 update as 6.0.1 is an emergency update to patch a bug in 6.0.

It purely depends on htc. Htc are responsible for sending the carrier a working rom for them to brand and bloat to their hearts content. Sprint may not be satisfied with htc produce.