In this context, I’d like to bring up a unit that is almost completely extinct in PvT: the Hellbat. Way back when HotS was first released, the Hellbat was actually used against Protoss. Their ability to handle Zealots synergized quite well with Marauders’ ability to handle Stalkers, and voila, Hellbat/Marauder was born. An unusual composition, to say the least, but it proved surprisingly effective against Protoss–at least until the Hellbat nerf hit and put an abrupt end to that. Hellbats were nerfed because they were taking over every matchup, and reversing that nerf is obviously a bad idea. Hellbat allins against Zerg, for example, would quickly grow out of control.
But there is a way to buff Hellbats solely against Protoss, and that is by adding +shield damage. This would allow Hellbats to regain their role as meatshields and anti-Zealot units, probably replacing WM in the early/midgame. The WM being what it is, I don’t think many people, Protoss or Terran, would be particularly sad about that.
Of course, the game is no longer the same as it was in 2013. The addition of Adepts, in particular, adds a new dynamic to the old Gateway comps. At first glance though, I don’t think Adepts will be a dealbreaker for Hellbats, since they are relatively short-ranged and not terribly fast.
I’ve got no clue if this is actually practical, but it seemed like a good enough idea to write down.