There still seems to be a bit of confusion, hopefully this clears things up:
- Since they are SO-DIMMs, you can of course upgrade the RAM yourself.
- Like the iMac Pro, Apple recommend that you upgrade the RAM through Apple Authorized Service Providers only.
- The bottom panel does not open in the same way as the 2012 model, and requires tools to remove.
- Removing the bottom panel voids the warranty.
- As for the ease of swapping out the SO-DIMMs once opened, I am told that it may require some disassembly, including removing the fan and logic board.