I guess we will definitely get deep gnomes and duergar.
Those characters are currently in the game and you can select those dieties as cleric.
Its only strange that we have not seen a surface gnome so far.
I really hope they include all PHB classes and races.
More is always nice to have (we already have gith and drow, plus probably other underdark races), but I would not bet any money on it.
There are datamined game files for about 37 more races / subraces from what was released online but models are currently only in game from what those files said currently for gnomes and durgar so i do expect we will see them first. As they could do a small patch add like 2 wizard subclasses and gnomes and it would not be a huge change but would keep people busy for a bit same with duergar and like champion fighter. Small impact changes that would distract people while a larger patch was worked on or maybe champion fighter and Necromancer for duergar. Those are small things that distract people require less work while larger patches are released and most of the foot work is already done.
That 37 is both races and subraces and counts the different dragonborn colors as different subraces so if you take that away its 25+ the dragonborn subraces color aspects. I see dragonborn as a big patch that if placed well with a good class could keep people preoccupied for a while especially if you throw in maybe adding level 5-6 to early access if you get exp to get that high combine those 3 things your keep people busy for 2-3 months where they ignore you.. (O and add some more in game items to the loot pools).