Nope, never, unless it it by some renegade priest, and it would be invalid anyway.
It wouldn’t be invalid until the renegade priest’s boss says so...in other words, the Church structure would have to act on it, and based on their laissez-faire attitude to the excesses of Vatican II implementation, who knows what would happen...
No, they wouldn't. It's crystal clear from all kinds of sources that two men or two women can't validly administer the sacrament of matrimony any more than someone can validly baptize a hamster. There's no doubt or ambiguity about it.
Nope, ain’t gonna happen. There’s a difference between the liturgical silliness that has been perpetrated in the name of VII, and a core belief of the Church.