For an inclusive BD figure, you'd need 2 jackets, could get away with one shirt and one pair of pants though, a second jacket isn't a big deal, they did it with Marcus. As for the arm, my guess would be they'd handle it like the Endo one with this figure, swap out elbow only instead of a complete arm, it'd be broken.
Here's what left to include with future T-800 figures in order to build his various looks in T2, that I can think of.
- Gatling gun and bag
- Grenade launcher and bandolier
- Grenade launcher with broken stock
- Gas grenade launcher
- Broken Endo arm
- Clean gloved hands
- BD gloved hands
- Semi BD portrait
- Full BD portrait
- BD jacket, whole
- BD jacket, torn sleeve
- BD pants
- BD shirt
Other items they could do but not necessary would be the machine gun they take from the SWAT van that he lights up the T-1000 with, they could include the metal pipe he breaks his arm off with, even though you could probably just buy something else to make it, he uses it to attack T-1000, T-1000 uses it to attack him, could make for a cool battle display. Also, if they don't make a John Connor, could add T1 CPU and Endo arm accessories as well.