So here's a list of champions that are affected by DFG (according to Riot) that have not been compensated yet, and potential plans for them:
Diana
Potential changes to Pale Cascade (W) but not sure yet. There are whispers a rework is in order but no one knows for sure
Katarina
A miniature, Lucian-esque rework is expected on the PBE this cycle
LeBlanc
Nothing.
Mordekaiser
Potential buffs to Iron Man (passive) but nothing in stone. Does supposedly have a relaunch forthcoming.
Syndra
Riot hasn't said anything yet about whether or not Syndra will be compensated, although she probably will be. Someone brought up the idea of Force of Will scaling with the thrown unit's maximum Health, which sounds like a cool addition both thematically speaking and gameplay-wise.
Twisted Fate
Possible changes to Stacked Deck (E) and addition of interaction between that and some of his other abilities.
Veigar
I heard about a possible buff to his Event Horizon that lowers enemies' Magic Resist, but I'm not sure how valid that is