I always thought the "if it were the case" thing was just a way of sweeping the knowledge problem under the rug by restricting counterexamples to "plausible" things that "would happen". It gives the appearance of a definition of knowledge, while simply moving the problem into the "plausibility" box (which you need to use your knowledge to evaluate).

I'm not sure it's useful to try to define a binary account of knowledge anyway though. People just don't work like that.