Hussar
Legend
A given thing might be "old" to us what have seen it before, but remember it's all new to someone to whom 5e is their first exposure to D&D - or RPGs at all, for that matter. So yes, even though we've seen D&D Dwarves written up 5 or 6 times already we're gonna see them again...and that's a good thing.
Lanefan
Fair enough.
But, if we're going down this route - the new gamer who is coming to D&D fresh couldn't give a toss about any of what came before. None of that has any resonance at all with the new gamer. So, everything is now on an even footing - no legacy issues.
So, why should dragonborn get the boot, but, say, gnomes get the nod? We already have a small race with halfings - something that has the backing of Tolkien to give it gravitas. We have a magical race with elves - again, stock fantasy race.
OTOH, while Dragonborn have none of the genre links that I can think of, the game IS called Dungeons and Dragons, so being able to play something draconic isn't too far of a stretch, particularly for a new gamer. Plus, it has a fairly distinct niche - it's the only "scaley" race (which, does have lots of genre appeal), and it's a "warrior" race, (again, genre fitting).
If we restrict the issue to purely points of value, and ignore all of what's come before, I can't really see why Dragonborn are any less viable than half-orcs or gnomes.