Going for a larva buff from 3 to 4 does sound like something that quite harmlessly could be tested, though I fear like others that it could inflate possible droning scenarioes in particularly PvZ where economy could quite easily go out of hand, but this is said during times where Protoss has performed post-satisfactory and thus renders the argument more invalid than initially intended.
I of course do not think Blizzard is telling us here that Zerg has no chance versus Terran, at best they are implying that this is the feedback they are working with, making it much harder to come up with good ideas.
If it is an official Kespa suggestion to go with 3 to 4 larva, then by any means it could be worth testing.
Personally I believe it is time to ask questions related to this feedback, in this case ZvT: - In which specific scenarioes do you think Zerg has trouble against Terran? (Liberators, hard to take 3rd base hatchery, drops, etc.) - What is the most target-specific solution we can come up with to fix said problem? (In this case I doubt 3 to 4 larva is narrow enough.)
I believe the same can be said for the recent feedback in PvZ. The Immortal nerf is there and can barely be felt, and we still struggle to see whether P or Z is strongest in this matchup.
To me, if Protoss does proove to consistently overperform against Zerg, I believe there are a variety of possible changes/nerfs to Protoss I believe are worth exploring as they do not directly nerf Protoss maximum strength per se, but rather limits the ease as to which this strength is displayed in games. These changes have already in some way or other been proposed by Blizzard, and could potentially be revisited again:
This change would make Phoenixes still "move and shoot", but would require micro similarily to an oracle. It would keep some mobility as you order it to attack, but it will not do it automatically through move commands. Such nerf could help Zerg making mutas versus Phoenixes, while also improving the Phoenix vs Phoenix situation in PvP.
This twilight upgrade is without doubt the strongest by far right now, and if anything it would make sense per design to see it equalized in cost and strength with the other twilight upgrades. In SSL 2 days ago we saw multiple examples of how strong adept timings can be. The best way to nerf Adept in this case would be to nerf the timing so that the Adept in general stays strong, but timings of a variety of builds does not.
I believe there are similar ways at looking at specific game problems in SC2 as the examples above where target-specific changes would have much greater impact on the game as opposed to more macrooriented changes like I could believe the larvae count from 3 to would be.