I think it's more that the bottom of the market has innovated faster than the top. The difference between a $300 phone with contact and a $50 one these days isn't nearly what it used to be.Phones in general are seeing declines and the high-end seems harder hit. There's not enough to really push the market, all the growth is in cheap phones and Samsung hasn't been doing well there.
I also wonder how much the carrier changing the way they sell the phones is impacting all this.