Samsung is slowly but surely taking over the
Analyst Benedict Evans first posted this chart. He believes a big part of the rise can be attributed to the fact that Samsung doesn't mention Android at all in its marketing. He believes Samsung doesn't talk about Android, in part, because Android is commodity software anyone can use. Instead, Samsung focuses on attacking Apple and promoting its own hardware.
Is this bad for
On the other hand, who cares? The most important thing is that people buy Android phones.
In a weird way, this could actually help Android. One of the looming threats for Android has always been Samsung "forking" the operating system and making its own version. Samsung would use the base version of Android then create its own OS on top of that, just like Amazon did with the Kindle Fire. The advantage of forking is that it lets you stand out from your rivals.
If Samsung just dominates the Android brand then there's less of a reason to create its own unique version, which means there's one less piece of fragmentation for Google.