Despite the fact that the Galaxy S4 has been highly successful for Samsung, it still wasn't as much of a blockbuster as Samsung had hoped. Because of this, we have reports that Samsung is now being more conservative with their estimates on the Galaxy S5 next year and will instead focus on building more mid-range phones and tablets. In fact, Samsung's newest estimates do not show the SGS5 sales increasing over the SGS4 as much as the SGS4 did over the SGS3.
Even though Samsung is being more conservative about their estimates, it's interesting to note they still have large numbers on the brain. Samsung expects to ship around 360 Million phones next year, which is still a 20% increase year over year. During that time they only believe that their premium phones will be 35% of their total sales.
Source: PhoneArena