Ok, the only animatronics without skin are:

-8-Bit Baby (DISCARDED)

-Jack-o Chica and Jack-o Bonnie

(DISCARDED)

Golden freddy

(Probably, but it just came out so I don't think so)

-Plushtrap (This one is quite likely)

Then the animatronics that only have one skin are:

-Circus Baby (Quite possible, since there is a Ballora skin)

-Mangle (I think this is going to take the skin, since it is the only Animatronic Toy to have a single skin and its skin for the Haunted Forest was canceled due to the winter event, VERY likely)

-Bare Endo (also very possible, since their last skin was in summer, they could make a counterpart of Flamethrower Endo)

-Freddy Frostbear (DISMISSED, already has a skin in this event)

-Ballora

(DISCARDED, already has a skin in this event)

So the most likely saying all this is that they will release a Mangle skin, and the second most likely is that they will release an Endo or Baby skin. (Also odds of a Plushtrap skin)

SPRINGTRAP DISCARDED, IT ALREADY HAS 3 SKINS, THE ANIMATRONIC WITH MOST SKINS IN THE GAME (and I don't want another skin like clown springtrap lol)