Im gunna keep this simple and easy since the OP's topic title made me facepalm (no offense).
If you know not to stand in fire and can dps where you're niche should be, if you're a tank and can control adds and/or boss as you should and know when to use your CD's, if you're a healer who can maintain evenly flowing heals and keeping the tanks up w/o OOMing in 30sec then ICC should be a breeze.
If I can do 17million in healing in TotC heroic in T8 gear and basically solo heal both tanks on more than one occasion through various phases then I can do ICC no problem and I am not worried at all. Only thing I am worried about are casters ninjaing my ring/neck/cape upgrades in the first few weeks with dkp lol. Going on vacation due to college has me undergeared currently so ICC is an exciting endeavor .