Android M Is Probably Next
Samsung hasn't confirmed anything but we're pretty confident that Android M will be the next update in line for major and mid-range Galaxy smartphones and tablets.
The Android M update is rumored for August for Nexus devices which means that we could see Samsung push out some Android M updates this year.
Android M should be on your radar because it's expected to deliver performance boosts in key areas. It also could fix problems with Android 5.1.1 if they appear on your device. Major Android updates always come with bug fixes.