I can answer both those questions.
One, 8P+K is no longer guaranteed. I know this because they removed that function in DOAD ; it was never intended as a feature of the move, it just so happened to work. Considering they moved it one iteration later, the chances of it being guaranteed are almost nothing.
And two, it wouldn't be necessary since we can combo into the air throw. We used to avoid it since you couldn't use an attack like 8PP then use the throw (except in tag), but now that attacks can precede it, we should be using it every so often. That means that even if the divebomb still functioned like it did in DOA4, we wouldn't need it since the throw (and Hiten H+K) deals more damage anyways.