The ONLY way we would know would be if we knew how many people were planning to vote for Hillary and didn't. If it were millions that would be meaningful. If it were only a coupla hundred or a coupla thousand what would that have changed? So we can't KNOW but we can guess/opine/surmise/conject. Same thing with the Comey interferences. All the rest will forever remain unknown. However IF you could see into a future where neither Russia nor Comey were involved at all would you want to know THAT outcome? Because?