Actors and actresses drop out of the limelight all the time, and such is the nature of Hollywood that no one ever really stops, notices, and thinks to hire them. It's depressing and terrifying, to say the least.
The reason I started worrying about Rene Russo is actually quite bizarre. It was thanks to Jennifer Aniston, who didn't pacify my feelings on Pumas by hiring Michael Sucsy to direct her in Goree Girls. Yes, I'm a hypocrite -- one minute I'm railing against her persistent lonely girl rom-coms, and the next I'm all "Aniston as a singing Texas inmate? That's so ridiculous. Who would I cast, though? I don't know. Probably Rene Russo or something." And then it hit me ... what the heck happened to Ms. Russo? I went to IMDB expecting that she had things in pre-production, or had several films languishing in direct-to-DVD land, only to discover she hasn't appeared in a film since 2005. If IMDB is to be believed, she has nothing on her slate. Her message board is full of "Did she retire?" queries. The most recent story on her newsfeed that's actually about her is from January 2009 when she told some red carpet reporters that Jessica Simpson looked pretty.
My imagination tells me that she's left the big screen because there aren't enough parts for women "of a certain age," and she's dissatisfied with the scripts that are sent her way. I really hope it's a personal choice and not that filmmakers have simply stopped hiring her. The Adventures of Rocky and Bullwinkle didn't stop anyone from hiring Robert De Niro ever again.