So is it safe to say that if an IW occurs during the last timed down of a quarter that the quarter will end with an untimed down?

If A takes the results of the play, we extend the period (even if A doesn't make the line to gain after 4th down).

If A chooses to replay the down (or we are forced by rule to replay the down because it is loose), we extend the period.

If A/B fouls and it is accepted we extend the period.

If A/B fouls and then we have an IW, we extend the period.

Yes Mike, That pretty well sums it up. One thing that keeps being said is that "if A didn't make the line to gain"...the down didn't end on A's merit (the IW killed the down) so how do we know if A made the line to gain. Another reason to see the ball dead before you blow the whistle.