Things might be stabilizing, maybe, but there aren't any great rivalries. I think that's one litmus test of a golden age. I'm not even sure we have any budding rivalries except maybe Azarenka and Sharapova (oh, brother) and Azarenka and A-Rad. It's a shame, because Azarenka, Sharapova and Serena are all great candidates for a rivalry. They have the right attitude and swagger. Serena, in particular, deserves an amazing rivalry, like Federer and Nadal have enjoyed. Every great career has a great rivalry. The closest Serena has had is Venus, and that doesn't really count because their relationship is different. Serena and Sharapova have the tension but not the competition. What was our last great rivalry - Henin-Clijsters, and Seles-Graf before that? Does Hingis and the Williams Sisters count?
I think Serena and Henin had a good rivalry going for a while.
Yes, probably the greatest rivalry of Serena's career (not counting with Venus).