If you’re looking for another clue, you might want to check out the Spigen cases for the upcoming flagship on Amazon. The description clearly reads, “Premium Protection SF Coated Non-Slip Matte Hard Case for Galaxy S5 and Galaxy S5 Prime (2014).” This not only confirms a “Prime” version, but it might mean that we will see it sooner rather than later.
Taking a look at the phones, all images on the page show a dual-LED flash below the camera lens, but they are also showing two different models. One has the hardware button, and the other doesn’t. I am beginning to wonder if the fingerprint scanner will only be on one of the models, namely the “Prime”. Of course these images could be just place holders, but we can speculate right?