T-Mobile provided us with the clearest look of the Galaxy S6 yesterday and one can just make out the hardware Home key. Samsung has to keep it, because it houses the fingerprint sensor, but this time it looks taller than usual.
That gave rise to the speculation that it will not be a swipe sensor like the Galaxy S5 and Note 4, but instead will work with a stationary finger. We've already seen such an implementation from Meizu on the MX4 Pro, which also features a taller Home key.
Some makes have chosen to move the fingerprint sensor to the back instead, there's plenty of room for a tall sensor there. On the front, the drive for thinner bezels leave less room for tall buttons.
Samsung recently bought LoopPay, an Apple Pay competitor, so we expect the Samsung Galaxy S6 to be even more focused on fingerprint-protected payments.