You can't cancel out a live ball and after the play with a change of possession[/QUOT
This gets somewhat technical. The Late hit occurs before the next line to gain is established. The unsportsmanlike penalties are enforced after the next line to gain is established.
So if the late hit carries an auto first down then the offense retains the ball, even though it is a dead ball foul, with a new set of downs.
I have looked and I cannot find a written source that says where a defensive late hit in the NCAA does not result in an automatic first down.
They made the late hit an unsportsmanlike conduct penalty. That penalty is enforced after the next line to gain is from the succeeding (next) spot, which is established immediately, or after any in play penalty, which late hits nearly instantaneous to the end of play.
If the defensIve late hit is properly called and enforced, the ball does not turnover. That the penalty becomes UNSPORTSMANLIKE changes how the first penalty is enforced.
The on TV explanation did not address the difference.
++++++++If someone can provide a link to a written authority (ncaa rulebook/casebook, (NFL rulebook may not have the same enforcement.)))++++
If I can get that information, I will gladly track my position. PS I have looked ending in frustration in getting a complete answer.