There is a heck of a lot of potential for the Seraphon for sure. Developing their aesthetic to be more like the modern models in the line like Kroq-Gar (Oldblood on Carno) and Tetto'Ekko/Starseer would go a long way to make them stand out as a unique creation and their background definitely leaves them open to new and exciting things. Take a look at the discussion on
Seraphon technology in the background form for starters and that's only scratching the surface!
My concern is that they will be left behind in favour of new ideas. New stuff like the Kharadron Overlords, Sylvaneth and Stormcast are all very cool, but it does feel to me like there's little intention of updating older armies at the moment. It's somewhat disappointing to see Stormcast on their third battletome (if you count Extremis Chamber) already while Seraphon basically have a glorified version of the Lizardmen PDF. Sure there are other armies worse off than us, but I can't shake the feeling of "We've done them. Next on the list!".