Those answers are horrible! and actually, not helpful at all.
This is what I think, I think that this problem will solve itself. I think that as new parents this is more about you then about a problem that will only arise in about a year's time and that you are trying to figure it out as a way to put yourself in that "daddy" (or dada or pappa or dad) roles. I think that as this becomes less new this problem will not be there anymore.
I called both my parents by their name till age 7, now I call them Mom and Dad, I know people who calls their parents " mommy and pappi" and people who calls their parents by their name, I have one friend who calls his parents "the old man and the bitch" Non of those parents anticipates that (especially not the last one, I'm sure) it just happens, kids and parents figure it out as they go along.