I think Jun is the last
Jun and the rest of Gamma company left on Onyx. So... about 10... ish... There was the one team that was crygenically frozen and captured, and one that is still in the shield world with Halsey and the girl from Beta company. And Jun, of course... yet we don't really know what happened to him...
I agree with the guy above me. That all is true. Noble Six is a possibility, all-be-it very small.
Noble six was confirmed KIA after making his heroic last stand outside CASTLE base on reach. So noble six is not a possiblity.