Of course I can't comment on the post in Announcements about this, but I wanted to add a caution from when I changed mine.  Make sure that all your games etc are on your list before the change is made.  Unless this has been changed, and I doubt it has, the change only picks up from your list.  For some reason that I don't recall now, there were a couple of mine that weren't, and it was rather messy.

Your current sticky list will not change.  If you don't have a game on your sticky list when the change occurs, it won't be on your sticky list afterward either.

However, your user name, once changed, will change across every post, every game, every PM you have made that is still in the system -- including games that are inactive.

This may have changed, that was a long time and several updates ago, but IIRC the game that was not on my list at the time of the change was in some sort of hybrid state.