[ImPostingOnHN]

the poster you replied to did not say that we needed 4 stomachs to digest grain, either. you're reading way more into their post than what was said.

it seems your misunderstanding results from the phrase "we'll be set", I think you took this general phrase to mean "we'll all be able to eat grain", yes?

if so, what the term actually means is, "we will be well prepared for the future", something that being able to eat grass would hypothetically help us with, since it would theoretically open up even more food options to more people

[ceejayoz]

It was a direct reply to an article about eating less grain-fed meat and redirecting that crop production to humans, implying we'd need ruminant stomachs to do so.

I'm not sure why some HN discussions turn into a lesson on object permanence.

[ImPostingOnHN]

in the spirit of HN, your inferences should assume a good faith interpretation of a post, like I described

in this case, since growing 4 stomachs is obviously not a serious suggestion, the post was flippant, like,

"now we just need Mr. Fusion bionic stomachs and we'll be set [so we can burn trash, in addition to grass, in addition to grain... this bracketed part is the implied portion of the joke that usually doesn't need to be said]",

since the term "then we'll be set" is almost always used to describe the next step in improving something.

improve upon what, you may ask? your own idea! lol. the humor of the joke is that the suggestion is silly.