Re: There is a solution to this
Replying to myself. I am wrong. There are several aluminium alloys which would make for a stronger iPhone 6 and 6+. Unfortunately they are devilish hard to work with and they are mainly used for lightweight armour in the military field. The cost per iPhone would increase significantly, and it's even possible that the stuff, and its machining and forming techniques, isn't for export to China, though I'm sure Mr. W will correct me on that.
Perhaps this is the plan; having sold Joe Punter a £700 phone, sell him a £700 NATO-approved case to protect it.