I was wondering if this was some of the reason VZW hasn't officially released the 6 yet.
On a serious note, it's anyone's guess why Verizon hasn't released it yet. My feeling is they don't need it. Regardless of how much we Nexus and Google enthusiasts think of Nexus devices, their really isn't a mainstream demand for them. With exclusive deals comes more revenue for Verizon, that's why they push the Droid brand so heavily. If Verizon had followed what they had done in years past and given us the Droid Turbo in August, then the likelihood of the N6 being released around Christmas would have been higher, of course that's just my opinion not fact. However, a lot didn't go Verizon Nexus enthusiasts way. Several phones were released around the same time that were more high profile, more in demand. That bumped them back.
Also, keep in mind Verizon is NOT excited about releasing any phones that are not locked down onto their network. I see it as a gift that they haven't shut mine down from a network position yet.
If they release a 4000mah N6, it won't be called a N6. It will have carrier exclusive branding and name and it will definitely come locked down. It may be very much like the Moto X 2014 and the Droid Turbo when it comes to software. "Almost" a pure vanilla experience and in fact many things that will be nicer (again in my opinion) than pure vanilla like active display and moto assist. I wouldn't expect it until spring (late Q2) at the earliest.