Changing cultural norms

I was having a conversation recently about how certain attitudes regarding homosexuality and transsexuality appear to have changed pretty dramatically in just a few decades. There's still hostility, of course, but attitudes and the public expression of those attitudes seem to have genuinely shifted. Similar things seem to have happened over the years regarding certain issues involving gender and race.

This got me thinking. What modern attitudes that are widely accepted and considered relatively uncontroversial might experience a similar cultural shift in the coming decades? Any ideas?