I doubt a Gilneas warfront, as much as I’d like to see it, because worgen and forsaken are involved in the Darkshore one.
We had humans + friends vs. orcs + friends in Arathi.
Then nelves + worgen vs. undead + goblins in Darkshore.
I think a goblin vs. gnome storyline will be part of Mechagon. Not a warfront per se, but it will probably bring armor and themes fit for those races.
I could see a Myst Isles warfront with Draenei + Lightforged Draenei vs. “Iron Horde” (Mag’har orcs) + ??? (ogres?).
Also a Quel’thalas (not sure if set in Silvermoon, Ghostlands, Quel’danas or Eversong) warfront with shal’dorei + sin’dorei vs. ren’dorei + quel’dorei.
Another possibility is a tauren + troll vs. dwarf + gnome, since those are the missing classic races to be the focus in a warfront, but they are not really inimical toward each other and there’s no place where they can really clash naturally besides the Southern Barrens, but that place makes no strategic sense in the current conflict.