I'm sure Sideshow will finish the Fellowship, and what's more, I can guarantee there will be at least one more non-Fellowship character. At least. I hope Saruman is the next villain; he's much more important than the Rindwraiths and for me, he's the more interesting character, both in design and significance. Furthermore, he's a massively crucial counterpart to Gandalf. In my eyes, Gandalf and Saruman are as natural as Merry and Pippin - you can't have one without the other.
Of course, that's largely because I want nothing more than the wizard's duel in 1:6 format!!!