Sadly, I rather doubt anything Seraphon will be coming out in the next 4 months, and the way things have been going with older factions, it's unlikely we'll be getting any new models - maybe a hero like the Ogors, since it's less expensive to sculpt and cast a single-pose model, much as we need updated battleline models.
And being honest with my self, I'm leaning towards a pessimistic view of our update whenever it comes so I don't get high hopes and see them dashed like I did with Cities of Sigmar. It would be amazing if we got the Gloomspite Gitz treatment, but it seems unlikely given their penchant for leaving lizardmen in the background since long before AoS came out.