A lot of flagship phones are in the process of getting Android 7 rather soon than later. LG recently started the Android 7 rollout to LG G5 users, Samsung at least started a beta test for the Galaxy S7 and S7 edge. ZTE tweeted on their German Twitter page yesterday, that they will follow with an Android 7 update in January of next year, at least for their Axon 7 flagship, which has been a very popular competitor to the OnePlus 3 in recent months. An lets not forget that OnePlus also announced Android 7 to come to the OnePlus 3 soon.
VR fans n particular are very keen on this update, because ZTE has said on the ZTE community forum in the US, that Android 7 will be a prerequisite for Google Daydream compatibility, which they are working on for the Axon 7. However, at this point it is unclear whether the update alone will already make the phone compatible. Apparently certification by Google is needed as well.