This bug has been resolved. If the new 1.11.2 launcher STILL doesn't work for you Mac Users, follow these steps.
1. Open a Finder window
2. Press Command+Shift+G
3. Enter in the search window: ~/Library/Application Support/minecraft
4. Click the "Launcher.jar" file
5. The launcher should open as a Java tab.

This morning my launcher was updated. When I tried to log in by pressing the green "PLAY" button at the bottom middle of the launcher, a loading bar would pop up and say "Preparing.." and stay there without opening the game at all. I have closed and reopened the launcher and restarted my MacBook Pro but nothing is working. I have logged out and back into the launcher over and over and it is still not going past the "Preparing" message next to the empty progress bar. One of my friends with a Mac also had this issue today. If there is any way to fix this that I have not listed, please let me know. Also leave a comment if you also have this issue with the launcher not loading on OS X.