I'm sure there are, but those are the only two I'd want miniguns for. The whole minigun as a handheld weapon thing is almost cliche now, I don't want to have many figures with them, personally.
As for Predator and Terminator being overrepresented, maybe, and to be quite honest I don't really care if I get a Blaine or not, but there hasn't been a decent Arnold-sculpt T-800 in 12" scale so I definitely want one of those.
What it really comes down to for me, though, is that I don't think it's an appropriate weapon for either Rock and Roll or Roadblock. I don't mind them updating the accessories to more modern weapons, but they should be "in the spirit" of the original RAH figure as much as possible.