Possibly, possibly not. I would say it is generally unlikely before Christmas, but probably pre Valentine's. Please allow me to explain my air of flippant dismissal of rumours, and be terribly English allow me to apologise (sorry!) as well.
First Samsung have to get V6.0 (Marshmallow, henceforth known as MM) and make it work with TouchWiz on the every top end device since the Note 4. So N4, N5, S6, S6 edge and S6edge +. They could, and probably will release it for the s6 and it's variants first. Now in the US they have to let the carriers get their mitts on it and bork - I mean add their stuff to it. On any given international model the software will just work, but still international carriers like to add their bloat/highly useful apps, and make them part of the update ROM rather than an extra to install at the users choice.
Now given the above, it is possible that Samsung could take MM from Google and make it work splendily before Thanks Giving on every top end device, although I doubt it. Then we all have to wait for the carriers. Indeed a SIM free, unlocked, untainted Galaxy s6 purchased direct from Samsung at full price may well recieve the MM update later than a "branded" s6 from a carrier with the same model number simply because the carrier has rushed it through and approved it.
So all a bit complicated. Lets just say, yes well get it.
