well, at the very least there will be: a graphics plugin, Probably rice's. An audio plugin, probably Schibo's. An input plugin. Who knows which, there are so many, and most of them good. There might be 1964 OGL, not sure if schibo was going to continue with that. No RSP, as far as I know.
My suggestion as to what to get...
PJ64 SP1's plugin set. It all works.
Hactarux's RSP plugin at the very least. (from mupen64, I'm not sure what audio/video he uses)
Azimer's .55.1 audiofix from the Apollo forum. it's very good.
Nrage's input v1.82 (I think that's the latest). It's probably the most complete input plugin in existance.
Lemmy's plugin from Nemu. It works well with some things other's don't work at all with.
That's all I got for now.