With the Horde getting two new races with access to druid in BfA and the Alliance getting only one, the previous unwritten rule of both factions having an equal number of druid races has since been broken. With that, the Alliance needs another druid race to rebalance things, so I think normal draenei are one of the likeliest candidates if that were to happen, if the Alliance doesn’t get a whole new race with the class in the future. The Alliance can also use at least one race that can be druids, paladins, and shaman all at once (the Horde now has two).
"Why draenei?"
Well, draenei are a popular race. I don’t know the exact numbers, but I assume they’re in the top three of Alliance races behind humans and night elves based on their looks and current class selection alone, so giving them druids would pull in a lot of people to make new draenei characters or race change their existing Alliance druids. While their current culture is Light- and arcane-centric, I think there’s enough room in the narrative to depict some of them turning to nature worship similar to them learning shamanism from the Broken.
For the other Alliance races currently without druids, well:
Humans: Popular, sure, but I think they’re unlikely when worgen and Kul Tirans already have druids without paladins. Maybe if one of those two got paladins, most likely Kul Tirans, then human druids with an HD lion Cat Form would become likelier (sorry, worgen).
Dwarves: People cite the Wildhammer as being how they could get druids, but I think the only thing really standing between the two is the other unwritten rule that a race can have only 10 classes tops.
Gnomes: Ironic coming from me, but gnomes are one of the least likely races to take up druidism simply because their culture is so anathema to it. Also, even if they did get the class, certain individuals would whine over them having regular-sized animal forms instead of house cats and bear cubs.
Void elves: If the Horde playerbase couldn’t convince Blizzard to give blood elves druids after 10+ years, there’s no way void elves are getting the class in the future. And even if the crusade for the former was successful, void elves would still be unlikely considering Void and nature magic are depicted as meshing badly.
[In before diatribe about how they could be any class if they try hard enough]
Lightforged: I wouldn’t get my hopes up for this one when their culture is even more Light-leaning than their Draenic/Azerothian kin. At the very least, if normal draenei were to get a new class, then Lightforged should get monks at some point in the future since that’s another class that the Alliance now has one fewer race capable of playing than the Horde.
Dark Irons: Not as likely as their Ironforge/Wildhammer kin, but at the very least would probably force Blizzard to give us a higher-quality fire cat model.
Mechagnomes: By far the least-fitting Alliance race for this class. For starters, their bodies are all mechanically augmented and their home is an underground city beneath a junk heap that’s overrun with machines and mutant horrors, which doesn’t really scream “druid”. The argument that they could have robot animal forms makes no sense, either, when those aren’t found in nature and very likely aren’t something a cyborg could comfortably turn into and back. There are other issues that I have with this particular combination, but I could go on forever.
"What would their default forms be?"
Cat: The panthara from Argus, obviously. They use the cat rig and they already come in a multitude of colors.
Bear: I guess some kind of draenei-looking bear. Before you suggest that they could get elekks or clefthooves, neither of those use the normal bear or werebear rig, meaning they can’t even sit or dance like a normal druid in bear form, neither has the sharp teeth or claws that druids rely on when fighting in bear form, and both are a bit larger than a bear, so blue/purple/teal tendril bears are the most likely choice.
Moonkin: I honestly don’t know. Given their origins, it would probably be another use of the high arakkoa rig.
Mount: Talbuk, another no-brainer. Could have options for both the Outland/Draenor species and the Argus species.
Flight: Moth, nether ray, mana ray, or Draenor ravager (the flying ones that use the silithid/qiraji drone rig, not the ones from Outland). Moth is probably the likeliest since we’re supposed to be getting the ones from Ardenweald as a Flight Form option in the future.
Aquatic: I got nothing. Would probably just get the default seal form like Highmountain tauren got. One thread on MMO-Champion suggested riverbeasts, but those are all used for land mounts and I can’t imagine them realistically being able to swim very fast.
Treant: Botani, maybe?
I’m not going to exaggerate and say that draenei druids could singlehandedly restore the Alliance playerbase, but I can’t deny that they would still be seen as a welcome addition by many and earn Blizzard a bit of race change and boost money.
