Well, I'm not actually convinced that Avatar has ever made money for Nickelodeon. The cartoon is great and all, but did it move a lot of action figures? DVDs? (I don't know, I came in at the end, and had to pick up the action figures on clearance/eBay!) But now the content of shows themselves can drive streaming subscribers, as proven by the recent Netflix-inspired resurgence. So it's more like the world caught up to Avatar.
I just wish the world had caught up in time to save Gargoyles.
But hey, at least we're finally getting more animated stuff!