If there is meaningful competition in the smartphone market, and what you say about consumer preferences is true, then surely at least one competitor would make a user-replaceable battery and capture what is supposedly the vast majority of the market.
If what I say is true, the people are still apt to buy a new phone instead of a new battery. As before, once you've overcome the friction of having to buy something new, you're going to evaluate all the options.
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.
I’m pretty sure there would be plenty of players willing to make the investment necessary to capture the majority of the iPhone market even for only a couple of years.
Apple sells around 200 million model year units at a profit of around $400 per device. That's $80 billion in potential profit, less R&D costs.
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.
