I will continue to call him "Bruce". Just like that college friend who you call by their maiden name decades after their wedding, or that grade school friend who you call "Billy" even after he's tried for years to get people to call him "Will".
First knew him as "Bruce". Will always know him as "Bruce". No offense. I don't care what he calls himself. He doesn't control the metadata tags I have on him.
But most of all, from an IT point of view, why, oh why? Having to change people's network IDs sux. We can and do it all the time, normally when women get married or divorced, but in the transitioning gender situation, why bother? Why change your first initial? Then you don't have to change your network ID at all, and there would be no issue.
Also, think about those monogrammed towels that you don't have to replace.
Like why didn't Bruce (I know his first name was "William" but go with me here) go "Barbara" or if that's too staid, "Bianca"?
If not for you, set an example for those that follow you. Think of the poor IT people. (Or the person who had to go thru and edit Bruce's wiki page.)
But if you're going to do it, go big or go home. Don't go with "Caitlyn". If he REALLY wanted to stick an ice pick into his ex-wife, rename yourself "Chris Jenner".
But, to be fair, if Caitlyn Jenner wins the Olympic Decathlon, I'm willing to update some of those metadata tags.