Wasn't there a racial "rarity" list being discussed for 5E at one time?
You are right... they mentioned common/uncommon/rare races at some point.
If they continue with that plan, one thing they could do is:
- give each Common race a full PHB entry (1-2 pages), subraces, and racial-restricted stuff (feats, prestige classes...)
- give all Uncommon races 1-2 shared pages with only their brief description, no subraces, no racial own stuff
- feature Rare classes in the DMG or MM (but if space allows, at this point would be ok for me in PHB too)
What races are we looking at being in the PHB if they go with "has to have been in a PHB(1)?"
I don't think that sounds a nice criteria for Common, but could work for Uncommon.
I think the best would be Common = have been in ALL editions' PHB, and Uncommon = have been in ANY editions' PHB.
Hence,
- Common: Human, Elf*, Dwarf, Halfling
- Uncommon: Dragonborn, Gnome, Half-Elf, Half-Orc, Tiefling
- Rare: get creative... Orcs, Hobgoblin, Genasi, Aasimar and some playable undead race would be my favourite candidates
*Drow as Common if an Elf subrace, Uncommon if a separate race