Yeah, dragons being sterile is a non issue, because Blizzard would just write around something like that if they feel that that little lore factoid interferes with their grand schemes.
Again, in Battle for Azeroth we suddenly discover a massive cache of Twilight Dragon eggs, and we have no idea how they got there. They're just there, and suddenly they're a major part of the story. Also after we defeat N'Zoth we find ANOTHER cache of Twilight Dragons whose minds Wrathion begins to clear of corruption.