I think, as mentioned earlier in this thread, that Britain could have sustained more infantry and fighter casualties and survived. The number of pilots lost would not equal the number of planes due to the proximity to the channel and that would have allowed the British to keep fighting ala the Battle of Britain. The number of planes being manufactured around the time of the Battle of Britain was staggering, as long as the pilots were picked up and brought back home, defeat for Germany in the air would be almost inevitable.

Of course, Hitler’s attack on Russia sealed Germany’s fate, but it would have taken an invasion of absolutely massive proportions for Operation Sea Lion to be successful so I don’t think that more casualties at Dunkirk would have swung the war, would have delayed it though.