In the particular example of a "family farm" (mostly extinct since the 1970s in any meaningful way), profit margins were always slim. Furthermore, life insurance for grandpa isn't likely to cover the difference... the real estate value of smallholdings is positively astronomical in many cases (acreage alone does this, but it's often high quality land in many ways).
There's not many plausible routes to "paying the millions-dollar death tax so that developers don't turn the cornfield into a suburb" in such scenarios. Mostly moot though, this all played out and was over before most of us were born. I suppose there are gigantic 20,000 operations that "won't stay in the family"... but those farmers:
1. Aren't really living on the same piece of land that they farm
2. Having to sell off 1500 acres to pay the tax bill doesn't much affect their operation except that it's slightly smaller
3. Have someone custom combine it anyway... they're basically a management company that hires a bunch of contractors
4. Generally are incorporated in such a way that sole ownership hasn't been an issue since great-great-granpa died back in 1961
Family farms are, at this point, largely mythological.