A newly-leaked roadmap for Samsung’s Marshmallow OTA plans shows a couple of unfortunate changes. We originally expected to see Marshmallow for the Samsung Galaxy S6, S6 Edge, S6 Edge Plus and Note 5 in January, but the new documents are saying Samsung is targeting a February launch (with some even possibly slipping as far as March). It’s likely the company needed additional time for testing, something that isn’t all that uncommon with a huge upgrade like Marshmallow.
That said, the rest of the timeline should hold up fairly well, with Samsung’s 2014 flagship devices still looking at a March/April 2016 window.
Samsung will likely want to stay diligent in getting these upgrades out, especially since folks are now resorting to suing the company for their lack of proper support over the years. Still, these things take time, and Samsung isn’t going to rush an update out before it’s fully ready (which could lead to all sorts of nasty problems that you don’t want).