Its not the graphics that need a rework, its their quest syatem.
The side quests were tied to your overall level, meaning if you were overleveled, you could unlock quests to battles that were only explained way later in the main quest line. Also the Frozen Wilds expansion made more sense if you did them BEFORE the final quarter of the main story line, but the missions themselves were of a higher level than the endgame boss.
Regarding the main quest line, while its quality is noticibly much higher in Zero Dawn than the later game Forbidden West, the way they were structured meant that f you unlocked the extra dialogue (from talking to certain NPCs) out of order, the whole script felt a little jarring.
Tldr: the quest system of Zero Fawn needs a fuckton of polish, not the graphics
This. So much this.
Also, the one incharge of side quests needs a bloody promotion. The side quests quality in Forbidden West was overall as good as the MAIN quest quality in Zero Dawn.
The quest themselves (minus a few misses), the voice acting and mocap, the POLISH. swoon