While in Smartphones themselves the battle may be only between iPhone 5 vs Samsung IV, when it gets to apps people are much more picky. Facebook is losing dominance by the week to focused niche players.
For most people Facebook Swiss Knife approach is good, but given a choice, a tool set is better. What is Facebook to do? They are lucky enough to be seating on a cash pile and it is a public company worth over $50bn. They have to do what Google has been doing for years. Buy, buy and buy. Instagram was a good start. Buy first and figure how to monetize later, learn from Google’s acquisition of Youtube which for years was as struggle and now is a star.