The Q continuum definitely are interested in humans, otherwise they wouldn't they wouldn't have made first contact with humanity in "Farpoint". They choose Q (De Lancie) to be their representative, who turned out to be pretty poor at his duty since he began to feel for the mortals after all his experiences with them. I see their interest in humans continuing as long as they are watching. Maybe they think studying us will allow them to learn more about themselves?
It's the other races they don't seem to give a damn about.
However, I don't see them appearing out of no where to save the day. That's never been their style with perhaps one or two exceptions. They've always caused more problems than they have solved.