OnePlus has confirmed that Android O will be the last major Android OS update for the OnePlus 3 and 3T. While closing the door on future OS updates after Android O, the company did say that the OnePlus 3 and 3T will continue to get security updates for the "foreseeable future". Even with Android O, the OnePlus 3T will receive just a little over a year of support, which is not much. Buyers of the OnePlus 3T probably would have liked at least two years of software support. During the Q&A, OnePlus also announced that it plans to push the August security patches to the OnePlus 3 and OnePlus 3T very soon.
Source: India Today August 12, 2017 05:26 UTC