This is not the end of it. As long as Brad and Toni keep caving, they can expect to be taking care of Shannon at least till age 18. But then the character of Shannon gives us more chances for Brad and Toni arcs.
I like that Bernice said no. Putting up boundaries is a very big concept in mental health care these days. It took me 64 years of living to put the concept into play and take care of myself. Comics don’t always have to be funny.
This arc is demonstrating what Shannon would be like if she was raised by Toni and Brad.