I know you and Slashdot have a fetish for removable batteries but is dishonest to pain this as a sealed battery problem.
It has not one single solitary little bitty thing to do with a battery that is sealed in place, versus a removable battery. Where on earth did you ever in a million years get that idea that I was arguing that?
It has 100 percent, not a shadow of a doubt, irrefutable laws of physics, total to do with a battery compartment that is simply and 100 percent clearly - too small.
So unless the laws of physics make replaceable batteries somehow not expand when heated, not expand when charged, simply not expand - a replaceable battery will do exactly the same thing when placed in a compartment that is not capable of accomodating it's laws of physics bound expansion.
Don't imply that there' some vast conspiracy to keep better products away from the public. The consumers speak, and they want thinner phones with more battery life.
And they also want perpetual motion and to heat their entire house on 2 tea candles and a clay flower pot. You can't always get what you want.
You cant make "Want" alter the laws of physics. You can't just keep packing more power into smaller spaces and have no limits. You need to go back and learn just what chemistry is involved here. There are some real limits here. First of course is squeezing more power out of a battery. But as we do that, we can get to a point where a battery can be pretty dangerous. Li makes a nice powerful battery, but doesn't suffer fools gladly. Lithium isn't as nasty as Sodium or Potassium, but it's like Mr Bigglesworth - you don't want it to get angry with ya.
The electronics can be made less power hungry, there is some wiggle room there yet. But the amount of power needed to connect to a cell phone tower isn't changing all that much, and might actually increase as we end up with an overall noise floor increase with all of the wireless devices of all kinds in use.