The Moedbus/Traitor Guards have shown themselves already and we may have already seen an officer and the Mauler Stand-in
Traitor Commander/Officer/Commisar, appear right at the moment they mention the Kill Zone, maybe he can order the normal unit around him or buff them like the Beastmen Flag does.
Traitor Specialist, with their weapon (Melta, Flamer, Bolter, Plasma…) could easily be turned into a few different (Flammer would be the easiest)
Traitor Gun Team, maybe they would set up and start shooting (Basically a Ratling but they take a bigger time moving/don’t move)
Traitor Sharpshooter, like the Ratling but if he had a Skaven Jezail, would shoot at a lower rate and stagger more
If we see more Ranged enemies (as special, Infantry or another category) could we also get some Grenade lobbing enemies, the concept is already in Vt with the Gaz rat but could be completed with various type of grenade, even Chaos Grenade (Blight Grenade)