I've noticed that many people are upset about the condition of the Infestor and Corruptor. I've also noticed that the Infestor uses a long tendril coming out of its back for its channeled Neural Parasite ability, which used to be used for its Siphon Life ability.
The main concern for the Corruptor, like the Phoenix and Viking, seems to be its air-to-air attack is lacking. Blizzard could easily buff their attack, but it seems they've instead focused on each race's AtA unit having some way of affecting ground targets. Corruptor can become a Swarm Guardian and has its anti-building Corruption ability, Phoenix has Graviton Beam, and Viking has a GtG form. This is likely so they don't become completely useless once you've killed all enemy air with them.
So here's my suggestion: give Neural Parasite to the Corruptor, and the Corruptors' Corruption to the Infestor (or not). Why do I suggest this mad idea? From worst to best:
1. The Corruptor right now is more often built to turn into Swarm Guardians than it is for ATA. Everyone agrees the Swarm Gaurdian metamorphing from the Corruptor and not the Mutalisk is a little strange. By giving the Corruptor access to a strong ability we can make the tech tree a little more cohesive.
2. The Corruptor model is laden with tentacles. So it would make sense for the Corruptor to actually use them... like for Siphoning Life or Mind Control.
3. The Infestor is a weak ground unit. Needing it to unburrow and channel its mind control is just silly. The thing is clearly a stealth and support unit, give it abilities that can do so, or at least make how they're used somewhat reasonable. The Corruptor on the other hand, is a strong mobile AtA unit that could actually make good use of Neural Parasite or Siphon Life. If the SG evolution was removed, you'd never be building many of them, because they're AtA only. Either Channeled or on a timer, letting those Corruptors not only take control of enemy air units but possibly ground units could lead to very interesting strategies. A unique mechanic like having their main AtA attack Siphon Life could also be quite interesting.
Anyway, the idea isn't wholly fleshed out or balanced so just let me know what you think. Genius and madness are two sides of the same coin.