Whenever I look at the electoral map, awash in red but shot through with blue blotches, it calls to mind the image of a cancer patient being steadily consumed by metastases. Is radical surgery the only hope for cure? The only problem I see with your suggested approach is that farmland could simply be nationalized as an emergency measure, and then equipment and operators would be brought in to farm it after the uncooperative original occupants had been eradicated (just think of custom harvesting expanded to include the whole cycle). Now if people simply torched their harvested crops in protest without planting a replacement in season, they might make a small dent. But I fear that the Starving The Monkeys approach isn’t going to do it at this point; I have this sick feeling that the path America is currently staggering down leads to bloodshed or serfdom, and possibly both. Unfortunately, when I look at America today I see a giant Yugoslavia, just waiting to fracture. I still hope for a Czechoslovakian outcome, but can’t deny the demographics and crime data indicating that there is an element who would be more prone to the Rwandan approach to settling irreconcilable differences.
I think a Zimbabwe scenario is more apropos to the situation on the USA, but it is far more problematic for the urbanites. There remains a large and homogeneous population in rural USA, and they are well armed.