The Kriegsmarine would probably have survived an attempted Sealion fairly easily, albeit mainly by virtue of being in dock getting stuck back together after various run-ins with the Royal Navy off Norway. The real victims would have been the Heer, who would have had the unpleasant experience of trying to cross the Channel in towed barges in the face of large numbers of RN destroyers, and the German economy, which would have been relying on said barges coming back to continue functioning.
I'm of the view that those who say Sealion could have ended the war in a decisive victory 1940 are absolutely right. It's those who say the Germans would have been the winners who are wrong.