I'm not sure where my folks stand, so thanks for creating this thread. :)
I've come out to them, and they said, ostensibly, the right things. "We love you and want you to be happy, whatever that looks like." But then the rest of the weekend I was with them they proceeded to act like the conversation never happened and made no attempt to use the correct name and pronouns.
Fingers crossed, the next visit with them goes better. I'm prepared to do some gentle corrections this time, now that they've had some time to mull on it.