I imagine it will be announced that it will. Announcing it, and delivering it is a different story. We might get it after the two years is up, but who knows. I still don't even have 5.1 so I am not too worried about 6.0.
Honestly, unless the next version of Android finally handles battery life better, I don't really care about it. To me, battery life is the only massive place for improvement and everything else is just little bumps here and there in specs, improvements, etc. Battery life is where the potential is. And i'm sick of hearing about Project Volta and then getting it and seeing no difference whatsoever.