Ghouls, feral ghouls, mutated people, supermutants, etc, anything not pure human die.
It does'nt happen immediately.
You get end slides that say the genome was cleared up, at the cost of many lives. Dead ghouls, supermutants, wastelanders, etc.
Then gradually as you play, you see wastelanders, etc dying. The people in megaton go to the doctor and get given aqua pura, and get worse and worse.
You should do it. It's good.
Evil but once you do it, it's fun.
It's as far as you can go with siding with the enclave, sadly.
Do it! Help President Eden and the Enclave!
Broken Steels awesome.
It was'nt just a dlc, it was fixing the major, braindead mistake that is the vanilla ending.