I agree that we'll see the grey ceramic again. Or perhaps a better way to put it is a color of ceramic in addition to white. But I HIGHLY doubt we'll ever see 18k gold again. I have a sneaking suspicion that Apple actually lost money on that model, given how many they seemingly gave away to celebrities.S6 should come with more new health measure function and Ceramic Grey come back
S7 might re design and comeback with Gold Edition
Should be like this
S0 18k Gold
S2 Ceramic white
S3 Ceramic Grey
S4 SS Gold
S5 Ceramic white + Titanium
S6 Ceramic Grey + Titanium
S7 18k Gold