30fps burst rate would mean roughly twice the throughput of the 1DX2, all things being equal. I think it's safe to say that that's not going to happen. Not without a catch anyway. If I had to guess it's similar to the 4K frame grab feature in the 1DX2 but stores the JPEGs separately instead of packaging them in an MJPEG container. Maybe it can even do RAWs. But reduced resolution, almost certainly.