A recent study by USC has showed that representation of women, ethnic minorities and LGBTI people in Hollywood remains stuck at about the same level as 2007. Clearly more needs to be done.
But what can be done?
It would really not be meaningful to just add a few more token characters here and there. This may fill the quota, but will really add nothing to our cultural consciousness. It's like how affirmative action programs often make things better on paper without making things better in reality.
I suggest that we should all help encourage more diverse voices and perspectives to enter the mainstream consciousness. Since many movies are based on written text, perhaps we should start there. Putting it in market terms, there's both a supply side issue, i.e. minorities often aren't as encouraged to write about their experiences as much, and a demand side issue, i.e. minorities' work don't get read as much, and don't often get widespread mainstream attention. The demand side issue is especially one that we can all help to fix, I believe.