From your perspective doesn't God look down that "corridor of time" and see who those people are who will fall away? Why would they be saved in the first place if God knows tomorrow they will fall away?
He does not wait for tomorrow. He sees where your choices have taken you (in your future). In other words He knows -- by seeing the begining and the end of times -- what choices you freely make and where these choices take you.
Omniscience does not equal predestination.
"From your perspective doesn't God look down that "corridor of time" and see who those people are who will fall away? Why would they be saved in the first place if God knows tomorrow they will fall away?"
God doesn't look down a corridor of time. What is time to God? This is an anthropomorphism, just like "pre" destination. It can only have meaning for us but tells us nothing about God or what God "sees".