Another thing that I am potentially worried about with the half-orc/elf move that WotC is making is that they may run into the Gnome problem from 4e D&D. There was no Gnome in the 4e PHB 1. There was a Gnome option in the 4e PHB 2. This came to bite them in the rear. I recall WotC saying with some hindsight regret that while Gnomes were played by a smaller percentage of players, that still meant that tables were affected by the absence of Gnomes in PHB 1. It did affect enough tables because it only takes affecting one player who wanted to play a Gnome to affect the whole table.
If there was something in the PHB 1 that just said "If you want to play a Gnome, pick either a Halfling or a Dwarf," I doubt that this would have helped matters at all. I understand that WotC is not getting rid of mixed ancestries, but I'm not sure if their "pick one of two pre-existing options" will necessarily satisfy people who enjoyed playing those ancestries/species/races.
At the very least, I hope that they are considering more interesting mechanical options than pick between two species, gaining their mechanics, and then calling it a day.