You are missing two huge issues for agriculture, labor and trade.
American Farm Bureau says that at least 10% of agricultural labor is provided by an immigrant work force. If Trump carries through with his promise to deport all illegal aliens, the affect on agriculture would be dramatic, and not positive (unless we create a real guest worker system that allows a larger, legal workforce).
Likewise, 65% of US soybeans are exported, not going directly to “factory farms” as you suggest. These beans feed growing middle classes in countries like Mexico. The trade wars Trump has promised to protect US factory jobs could have a negative impact on these exports. Corn and other commodities are same.
Of course, it is too early to tell how any of this will turn out. But understand that “agribusiness” is not a single monolithic thing in this country. It is many companies, farmers, and processers.