On the phone front, they were used to selling phones at premium pricing only relying on their brand name. You don't have to look past Nokia or Blackberry to see how that will end. They're not really innovative, and while their devices are generally quality, they've pushed the price point too high. Xiaomi does 90 percent of it for 30 percent of the price. Huawei does 200 percent for about the same price.
On the chip front, TSMC has been outpacing them for years, and is getting all the contracts.
The only thing I can think of that Samsung does better than anyone else is OLED, and others are catching up very quickly.
I think Samsung will join the ranks of HTC and LG as also rans in short time...