At this moment the developers are busy squashing bugs and improving efficiency, but they have expressed their interest in mod support but I don't know how far that would extend, because it would take time and effort to make support for each mod out there. There is no one size fits all type of approach so you can imagine that it would be pretty time consuming :)
We can only hope though!
From my limited knowledge of how the ReplayMod works, they should be able to add support for any mod that doesn't use custom packets, aka add support for Forge packets. But then any other mod that uses custom packets would probably need to be manually supported.
@User1 I would be interested in helping add mod support :)