My Fairphone 3 already has replaceable batteries. What is really missing is an industry-standard form factor, like ATX/ITX exists for desktops.
If there were a standard, we'd be able to upgrade the components as needed. We wouldn't be forced to waste perfectly good displays just because we would like to upgrade the CPU. Companies wouldn't be pushing for new upgrades every year. Apple/Samsung wouldn't be able to hold their dominance because it would be easier for smaller players to specialize in specific components. The entire maker community wouldn't have to be fighting over Raspberry PI and we could even have a cottage industry around upcycled consumer electronics.