We might see it, but likely just in Mythic, and even probably just with the last few bosses. I imagine Blizzard might be aiming for RWF being difficult by virtue of the bosses being completely untested on the PTR to ensure raiders need to adapt on the fly, rather than being difficult by just adding more mechanics to ensure raiders are still challenged with full knowledge.
Heroic is the difficulty I am the most concerned about. Mythic raiders are a tiny amount of the story layer population, whereas NM and HC are a fairly substantial amount, and the difficulty for those players is likely where Blizzard took the biggest hit.