A new version of Samsung's update schedule has leaked and it looks like sad news for Galaxy Note 5 owners. If the intel is accurate then the Note 5 won't get the Android 6/Marshmallow update in late Q4 of 2015 after-all. According to the leaked info, it has been pushed back to Q1 of 2016.
In fact, taking a look at this revised schedule it seems most of Samsung's newer devices won't get the Marshmallow update until the beginning of next year. We will keep an eye out for additional confirmation of this intel, but for now, it's probably safe to assume this is accurate.
Here's the dedicated section for the Samsung Galaxy Note 5 discussions: Samsung Galaxy Note 5 | Android Forum at DroidForums.net
Source: PhoneArena