Two possibilities. First, Google could go software only for older hardware. It will suck for them. But by the time YouTube phases out h264 there will be few of

Two possibilities. First, Google could go software only for older hardware. It will suck for them. But by the time YouTube phases out h264 there will be few of these and the latest hardware will accelerate both WebM and h264. Second, there could be a way to utilize the h264 hardware decoder to work with WebM through a wrapper. The ffmpeg decoder for WebM is basically a wrapper around the existing ffmpeg h264 decoder already. I've never worked with decoders myself, but this at least seems plausible. Regardless, I think bundling WebM software decoding along side h264 decoding in the YouTube iOS app is a no-brainer even if YouTube doesn't take advantage of it right away.