three surviving Resistance members from the Command Mission/Giga City incident (Marino, Massimo, Cinnamon)
Nana was working behind the scenes of the Resistince acting as Navigator, but also survived. I liked to theorize that she was enlisted as a navigator for the Maverick hunters... apparently MHX said that there was more than one Navigator assigned per job and worked more like a communications network of the Hunters themselves.
Also, Marino's weapons MIGHT resemble an X-based version of Harpuia's weapon, but I don't think it was fully confirmed that it was red and had the ability to shoot wind tunnels.
Zero 4 also touched on the subject that Weil was human, but transferred to a robot body. I can't see that happening without the aid of a spychic to guide the soul of the man to the mechanical monstrosity.. I always wondered how they did that, as it bugs the crap out of me sometimes. Metaphor perhaps?
Cyber Elf development is also I'd like to witness first hand when the cyber elf baby is first made... makes me wonder who.. or what made Jackson. He might be a rare elf, but his origins are just as sketchy as the Mother Elf's.