GSD - Pretty much.

A couple of the guys who I think are good fighters have a tendency to follow standing grappling down to the ground and end in a submission. You can see this in both Mike Patterson's and Tim Cartmell's video clips which I've posted a number of times. The latter studies BJJ and incorporates it into his kungfu, while the former does not. So it's anyone's guess whether or not this comes directly from the kungfu training. My feeling would be that some pure kungfu teachers would have figured out and taught methods of transitioning into and maintaining ground submission (it seems like a logical thing to figure out when you have thousands of years), however, based on what I have seen, these individuals are extremely rare. So in practical terms, you are right on in your description. The ground-fighting chinese styles that people often mention are more oriented in counter-submission and joint-destruction from the ground, and are quite a different beast than BJJ (and they too are very rare).