They have the sprites for Dragonborn race, the playable ones in DoS. BG3 game will use Divinity Engine 4.0 so I think it is a safe bet. Dwarves, humans, elves, surely will be there too.
They will be, not because they are in Divinity, because FR Elves and Dwarves look different. And Divinity had Lizards, not Draginborn, Lizards are more like Lizardfolk in D&D, both of which like different from Divinity Lizards. And they've said BG 3 will look different Divinity.
But you are right that all these races will be in, but its because they are in the PHB and any race in the PHB is basically a lock, so Humans, Human Variants, Wild Elves, High Elves, Drow, Hill Dwarves, Mountain Dwarves, Lightfoot Halflings, Stout Halflings, Forest Gnomes, Rock Gnomes, Half Orcs, Half Elves, Tieflings, Dragonborn will all be safely in because they are in the PHB, Dragonborn are seen as a core race now, they are even covered by the OGL for 5e.
That doesn't mean BG 3 will only have PHB races, it just means those races are a very safe bet.
