Unfortunately, the referenced post is about a year old. I am not sure why Unreal 4.8 got no support for Cardboard till today. In my opinion Every modern Android smartphone is capable for VR usage hardware-wise. Maybe there is some other reason of waiting for support.
I admit, it took me some time to get the important functions of the Android NDK for the tracking into Unreal and to get the stereo rendering right, but besides that the implementation has been pretty straight forward.
-Michael