Runaan's Hurricane shouldn't build out of Zeal.
TL,DR: The PBE changes are going to make the problems around Runaan's worse: it's overvalued and overpowered on crit-based ADCs and doesn't help on-hit ADCs.
A little late to the changes, but I have long had a problem with Runaan's since the AD "everything crits" update from preseason 6. So the old Runaan's (Recurve + 2 Daggers) provided a niche for certain ADCs, mostly Kalista and Twitch and maybe Caitlyn and Varus, to apply on-hit effects to multiple targets, which obviously helps their teamfighting and waveclear. The downside to this is that Runaan's didn't provide any crit, but when you're Twitch or Kalista, most of your damage isn't coming from crit, it's coming from pressing E after a few auto's and having a couple of massive AD items provide the base for the E to nuke for the stacks of passives applied to the targets.
Interestingly, I think one of the low-key reasons Kalista hasn't been meta despite Runaan's current dominance is precisely because crit chance is actually a thematically bad stat on her. On Kalista, you need to count on your auto's being the same damage; if one of her auto's crits and kills a minion you needed to get the E reset, then you lose out on having more follow-up damage in the fight.
It was super important for Kalista and Twitch to have a viable on-hit build like BotRK, Runaan's, and Bloodthirster to compete with the crit ADCs, and when Runaan's went crit, both Kalista and Twitch fell right out of the meta until the recent BotRK buffs.
The weird thing to me is that crit ADCs already have a waveclear/teamfighting attack speed item that was dominant until Runaan's got Zeal. Statikk Shiv was built in literally any game by any crit-based ADC to the point where Riot was trying to buff the heck out of old Phantom Dancer to make it a comparable buy, but the value of AOE damage and crit was simply too valuable to ADCs.
In fact, I think adding Zeal to Runaan's build is the sole reason Caitlyn is so bloody oppressive right now. Her passive benefits from both crit and on-hit effects, which gives here a lot of teamfight threat and lane presence even before considering her traps, which just make her nigh impossible to defend against her siege.
Adding Zeal to Runaan's made AOE damage more accessible to ADCs (every auto!) without penalizing their crit builds. That's a massive buff to crit users and a hard, if unintentional, nerf to on-hitters. So for Riot to finally notice "huh, Runaan's seems a tad overpowered" is about as newsworthy as discovering that water is wet.
So seeing that Runaan's is losing Recurve Bow and its on-hit damage on the PBE makes me sad because I don't think Riot is noticing this pattern. If anything, it's going to make the problems around Runaan's worse: it's overvalued and overpowered on crit-based ADCs and doesn't help on-hit ADCs.