But let's assume what the OP says is true. It is still not clear why anyone would do what you suggest? The investment required to be that player would be intense and knowing that you only have one product lifecycle to recoup it... Highly unlikely anyone is that daring. Competition sees players seek to be the winner, not the first loser.
You think you can build something at least as compelling as the iPhone from the ground up for less than $80 billion? Apple is spending $30 billion on R&D a year just to improve what they already have! Good luck...
And you only get one year to capitalize on that investment, more or less. By year two, without even more investment, the competition will have you smoked with their latest offerings. You might not even get a whole year if they see you as a credible threat. Nothing says the iPhone must be released on a yearly schedule.
But if the battery was working as well as it did when it was new, it is unlikely that the person would have started shopping in the first place. It is the catalyst that sees them move beyond "what I've got is good enough" to "this isn't serving my needs anymore".