That's just a potential outcome, pretty standard stuff:

http://www.stat.cmu.edu/~fienberg/Rubin/Rubin-JASA-05.pdf

"What would happen if hypothetically X were done" is one of the most common targets in statistical inference. That's a huge chunk of what Fisher/Neyman had done (originally in the context of agriculture: "what if we had given this fertilizer to this plot of land?") This is almost a hundred years ago.