The big question is whether Samsung can duke it out with lower-cost players and compete at the low-end of the market. At the high-end of the market there are also concerns. The Galaxy S5 has a design that is too similar to the S4 to warrant a big upgrade cycles. Tablet growth is slowing so that'll hurt Samsung too. When Apple comes out with a larger iPhone, Samsung will also have issues. Smartwatches aren't likely to save the day either.
Bottom line: Samsung, Android's lead dog, has a multi-front war in the smartphone market. It will have to develop different tactics going forward.