This is a very big moment for WebM. I feel 4chan has become the 'porn' industry of the internet. With VHS vs Betamax the largely deciding factor was which standard porn supported (this was again to a lesser extent with bluray).

The general lack of adoption of animated png's is often pointed squarely on 4chan. Since it generated most of the web's viral funny content. And since most of it was in .gif, who needs to support .apng?

Hopefully we will see the opposite with WebM. More general funny content, more drive for it to be adopted on sites like reddit (which already to some extent uses gifcat on some subs), and imgur. Which will snowball its general adoption.