Apple is likely to launch “Prime” after the original and the next model; maybe in next summer. Pillar to this flagship S5 Prime that is Samsung Galaxy Alpha will be there in competition with Apple iPhone 6 Prime. HTC is not going to lag behind and would launch its HTC ONE M8 Prime and similarly there are rumors about LG G 3 Prime. So all the “Primes” are going to fight a tough battle in summer next year.
It is said Apple is going to arm its prime with Sapphire glass and there are plenty of news about the production of Sapphire glass. It is reported that Sapphire glass would be produced exclusively for iPhone 6 but does not seem much logical. Reason being iPhone6 production has started about a month before and is likely to come in the market with in span of a month and if Sapphire glass is yet to be produced, it cannot be a part of iPhone 6. Therefore its exclusive use in the iPhone 6 does not seem logical and possible. Now the news is modified that Apple is in process of planning and producing the premium model of iPhone 6 and maybe heaving Sapphire glass; in any case currently in this year we are not going to see any Sapphire glass on iPhone6.
There is nothing much known that would make the next model “Premium” other than the use of Sapphire glass. Maybe the specs are refreshed and RAM maybe increased to 1GB in the next iPhone 6.