Anybody that knows anything about Samsung knows that they want to 'do it all' when it comes to the electronics field. They are not content to purchase parts from other manufacturers to build a Samsung smartphone - they want to design and build their own Super AMOLED displays, their own DDR4 RAM, their own UFS 2.0 Flash Memory, their own Samsung Batteries and their own CPUs and GPU chips. Samsung believes that they can build them better, cheaper (not buying them from someone else), and control their own supply channels and not have to rely on other manufacturers to meet Samsung's goals.
Samsung took their first big step with their new Galaxy S6 and Galaxy S6 Edge by bypassing Qualcomm for their own 64-bit Exynos 7420 octa-core processor here in the US, where the Qualcomm Snapdragon had become their main staple. As much of a step in the right direction this is for Samsung, they cannot claim all of the internal design - their Exynos 7420 still used the stock ARM designed core processors, whereas Qualcomm, NVIDIA and even Apple's A series, design their custom core, based off the ARM design. These proprietary custom cores are better suited to work within the rest of the processor design, making them faster and more efficient.
Samsung Electronics System LSI Division has been working on their own 64-bit core design for the past four years and appears ready to start using their proprietary core in 2016. We would most likely see the new cores in the next Galaxy S7 model, although they may find their way into the Galaxy Note 5 and Note Edge that will come out in the late fall, but that may just be wishful thinking. Samsung has the production capacity and is in constant expansion to produce the necessary chips for their own devices as well as other manufacturers of smartphones, many of which already are using many of Samsung made parts.
Many were reluctant when the rumors rose up of Samsung using their own Exynos processor in the new Galaxy S6 series - after all, the Qualcomm Snapdragon was the main player and a known quantity. However, overheating rumors of their new 810 processor - one day it does and the next day it does not - probably helped force Samsung's decision that it most likely will never retreat from, which will be quite a blow to Qualcomm's bottom line in 2015. Just as the Galaxy S series is now reaping the benefits of that decision, the addition of a custom core from Samsung could really boost performance and extend battery life even further.