In the case of Europe, it probably would be.
I don't think we'd get the access that we had historically. We have to live with the fact that the Europeans are very large producers of wheat and other grains. In terms of being able to re-enter that market, they are not going to move back to being a net importer, as they were in the 1960s. They are often the second-largest exporter of wheat in the world. In terms of market share, they are the ones we compete with.
Overall, the benefits for the entire economy would be significant. Very indirect effects come through; everybody benefits as overall incomes grow, and there would be a large share of agricultural benefits.