there may never be a million mile battery in a phone

 The reason is simple, the phone makers are not truly competing in a purely competitive market. If they were then things like the three and a half millimeter Jack and the SD card would be around forever. This is because they would be competing so fiercely that they would include every feature that would give them any tiny edge, but there are only a few real producers of cell phones.

Because they are not extremely competitive they do things to make them more money not give you a better experience. It's not quite that simple, since they go to incredible links to produce a better screen and they spend zillions of dollars on cameras. I mean if they were truly just trying to make the most money at the least cost they would give you mediocre everything and charge you world class prices. So we have sort of a strange combination of some world class stuff and some stuff driven by their desire to make money while giving you less. They're probably never going to take away the screen, the phone would be unusable. They're probably never going to take away all the memory for the same reason. They're probably not going to quit connecting to the internet. But with the nice to have things, like SD cards and extra device jacks they take those away because there are alternatives, like buying a bigger phone from them for hundreds of dollars more. They also realize that there is a huge market of people that just won't pay $1,000 for a phone. So for those people they come out with the sub $500 phone. but if they do the same thing they did with batteries the day is coming when there will be no SD card slots in any phones, just like there are no phones with removable batteries. Most people probably don't remember the day when all phones had removable batteries except for iPhone. You could keep a phone for several years, but then the phone manufacturer is lose out in selling you more phones. While iPhone was gleefully stuffing a new phone in your pocket every year the Android phones might last three or four years. This was simply unacceptable they needed to sell you a phone every year too. After all it's just not about you.

 And strangely enough most people don't want to use the same phone for 14 years. Even though the actual improvements in phones is tiny the perception is that the newer phone is way better. But if you go back and look at the Samsung Galaxy S3 which was around in 2012 it is still a pretty good phone to this day. It is still way better than the cheapo $100 phones. And it had a removable battery and an SD card slot. Now the screen wasn't that great, but guess what it was still pretty stinking good. Mine still turns on and works but it can't connect to the network because it doesn't have LTE.

 Frankly the phone industry is bilking us for billions of dollars, but it's a market that most people buy into.