What's next will be any internet multicast business who want to be on the platform: Netflix, LoveFilm, etc. And any free service that wants in too.
Subject to the Freesat guardian's approval, of course.
From what's been said and published, there's likely to be more online entertainment, catchup and film options but no live sports options.
I also expect more linear channels to join Freesat in the future including ones that are currently free to air and free to view. I also expect some of the local city news channels will join Freesat at some stage and there'll probably be a few more HD channels with even C5 HD eventually joining.