Originally Posted by
Loren Pechtel
Note, also, that he said between V1 and takeoff. If the plane in front has passed V1 it would take something pretty catastrophic for it not to take off.
He said "probably" between V1 and takeoff. No way to know unless you were in that cockpit.
The takeoff clearance was based on the "anticipated separation" standard mentioned above and, likely, diverging headings once airborne. The crew can see the airplane taking off in front of them and aren't going to continue the takeoff if there isn't enough room. It's also trivial to reject a takeoff at low (<80 kts) speed if the previous airplane doesn't takeoff.