Its called, "How can we make the storyline make sense for people that didn't play the first Crysis games, and by that I mean most of the console folks this has to be adapted to"?

They could at least explain what happened to Nomad and Psycho. They were the main 2 protaginists you used in the first games. Did they just fade into Oblivion? What?
yeah but it's 3 years on or something isn't it so Nomad is probably tired of violence and nano technology and has relocated to Korea because he actually like Koreans and thinks the women are hot.
Psycho went back home to London, his real name is Jason Statham and he made a few movies, got bored of killing aliens and nano technology. He gives the odd Korean a slap now and again. just for old times sake.
I hope this had filled in all relevant plot holes for you.