Sure, this isn’t a guarantee that we’ll see the same nerf in live, but the chances are high that this will be published to the main servers following rumblings in the community.
The precise change seems initially to be a minor one. When Mercy’s new ultimate, Valkyrie, is activated, beyond being able to fly and getting several buffs, the cooldown timer on her secondary Resurrect ability is reset. However in the PTR, this has been removed. If you pop a rez, then immediately activate the ult, you can immediately bring another team-mate back to life. Additionally, Resurrect’s usual 30-sec cooldown would be reduced to 10 seconds, meaning she could resurrect three players in rapid succession – which smells a lot like her previous multi-target rez ult, meaning technically the new ult made her indirectly retain her old ult.
While this on its own is pretty OP, coupling it with all the other bonuses yielded by Valkyrie, it made Mercy an absolute juggernaut. Well, a non-offensive juggernaut. A healernaut?
Ever since her new version went live, she has become a highly common pick as opposed to her previous version being often avoided, as it forced players to adopt a passive playstyle, waiting for their ult to charge and the chance to pop a five-man rez.
The new version would mean that Valkyrie no longer resets nor reduces the cooldown on Resurrect, meaning that 30-sec cooldown has to pass in all cases, and it cannot be reset or reduced at all. It was to be expected that such a drastic reworking of a hero as what Mercy went through wouldn’t result in a pristine setup on the first try, since she’s almost like a whole new hero now, and changes like this are bound to come in after a few weeks of being playable on live.
Mercy’s past month or so has been a tumultuous one, and the hero may go through some further changes yet. Keep an eye on the PTR to see what to expect in the future.