Let us assume that alien space bats persuade Grand Admiral Raeder to attempt the not too difficult task of becoming the most honest leader of the Third Reich. Thus he asks to see Hitler very soon after 22nd June 1940 and argues very strongly that it is absolutely impossible to invade Britain using all the arguments made here and elsewhere against Sealion. I suspect that he could have convinced Hitler.
What are the consequences? Would Hitler have made more attractive diplomatic offers quicker such as offering to withdraw from all his western conquests in return for a peace with Britain? Would he have started planning a Mediterranean campaign? Would there have been a Battle of Britain and, if so, how would German plans have differed if they had not been preparing for an eventual invasion? For example, might night bombing and mining attacks on British docks have been the main tactic chosen? How much would Germany have gained from not diverting barges and not diverting dockyard labour to modify them? Perhaps a less serious coke shortage might have occurred during Winter 1940-1 and slightly quicker completion of some warships including Tirpitz? Would the British have gained by releasing destroyers quicker from watching against invasion and thus suffered fewer destroyer loses to bombing and have lost fewer ships to U-boats?
Any other suggestions?