As usual, we get a silhouette preview of their Mod III art before they are announced one-by-one in a drip campaign - ain't nobody got time for that!
Let's take our best educated guess aas to what the candidates are.
Who Are They?
#1 - Calico M950A
With her firearm and distinct hairstyle on full display, this core member of the Kiritsugu Exodia is the easiest guess in the new batch.
#2 - GSh-18
Guessing gets a lot harder here because we can't see the gun itself, but it's obviously a HG of some type. Fortunately, the list of short-haired HGs who didn't already get a mod is pretty short already:
We can eliminate a large chunk of these purely because we are unlikely to get two 6-star Mods at the same time, and some of the limited HGs are out.
While this leaves a few, we can do better: there's an obvious hair bow in the silhouette, and only one of the remaining T-Dolls wears one as opposed to a hat:
#3 - M500
In the contrast-enhanced teaser, we can much more clearly see this silhouette. The firearm is obviously a shotgun of some sort, and there's only one SG that comes with the distinct animal ear shape:
This would make M500 the first SG to receive a Neural Upgrade. Isn't that exciting?
#4 - KSVK?
The final T-Doll also has animal ears, and fortunately for us, there are way fewer kemonomimi girls in Girls' Frontline than Arknights.
IDW already received a Neural Upgrade and G41/ART556 are unlikely to get one in this batch due to her rarity, narrowing our choices down to P7, TMP, and KSVK. (CR-21 is too new to be eligible for Mod.)
We can eliminate P7 and TMP because the ears appear to be organic rather than decorative, leaving KSVK as the only viable candidate remaining.
KSVK's very unique skill will likely get a big boost with her Neural Upgrade. Could this signal a meta change in the next major CN event? Only time will tell.
@Psyrhos correctly pointed out that M590 actually grows cat ears in her costumes! Guess the fourth T-Doll isn't so set in stone after all.