For Ubuntu 14.10, Debian imports will be frozen in a couple of weeks. So probably it won't make that release, but will be available in 15.04. That's being available in universe. Somebody might put it into 14.10 backports, as well, but that would only affect people technical enough to get ffmpeg anyway. Being used by default would be at least another release on from that, if ever.

That's assuming normal release practices. It could change a bit if Canonical decided to push it, or if a showstopper bug turned up in libav.

Based on the mailing list exchanges this sounds like a fairly contentious topic still. It's possible it will happen, but maybe not for another few releases.