Between Showers

The Real Outcome if Batman & Superman fought to the death

Yes, Batman is mortal and Superman has every power, ever. So yes, if the Kryptonian were to ambush the Dark Knight and use the full force of his powers on him, a caught-off-guard Batman would die. and so would Superman. Because that is the nature of the character. He knows his opponents and plans for every outcome so that even in the event he loses, he wins.