Its not even an option. I'm one of those people that need RAM. Lots of RAM. Its not my fault, but the OSs in the VMs I need to spin up want more RAM every year, and Apple's limits haven't budged since 2011. It is to the point I have to travel with a 2nd machine, because 16GB just doesn't cut it for my workflow. And 16GB is all they will sell me, so no upgrades in the foreseeable future.