My grandparents were still the type of people who did not buy vegetables. There was a garden in summer and a lot of canning at the end of it.
I think my parents were of the first generation that worried about grocery bills
It really doesn't take much. If worried about cost a huge chunk of Americans could easily grow stuff on a balcony or near a kitchen windows for herbs even if they don't have access to dirt. Many places also have community gardens for those with no backyard. Farmers markets with local produce are also growing increasingly common - this is where I get the vast majority of my produce in the summer and I don't find it's that expensive as the flavors go much further due to the higher quality. I also get some locally made pickles, pickled garlic okra and other veg to supplement during winter. Plus jelly and jam my grandparents make and send me. People don't even know what they're missing when they eat the flavorless modified varietals built to last on a grocery store shelf.
The other factor is that if subsidies are removed and demand for fruits and vegetables goes up, farmers may be able to focus on this to increase production and meet demand. This will have the added bonus of potentially better tasting produce because they don't have to be bred to last long travel times. Heritage varietals taste better and are more nutritious.
Add to this that there is interest in supporting local farmers and ranchers in moving to regenerative agriculture, some varieties of which you use the same land to produce both livestock and produce in a mutually beneficial way. This can help diversify yield and add some resiliency for the farmer - they're not all in one thing.
Lastly for those saying you can't make enough crop for humans and animals it's worth noting that for cattle the fast majority of "crop" they're eating is inedible to humans. It's stuff like corn husks and wheat stalks. They digest the cellulose we can't.
For pigs and chickens they can eat food waste. In some areas they take expired stuff from grocery stores and feed it to the pigs and chickens to reduce wasteage. Not sure about in the US, but it can be done.
