Mech-action sequel was in development at one point.
During a well-attended talk on the TGS show floor over the weekend, Hideo Kojima revealed that he still intends on bringing Zone of the Enders 3 to fruition.
The producer of both Zone of the Enders and its sequel, The Second Runner, admitted that the third game in the series was in development at one point.
The large crowds at the talk impressed Kojima, who has been spurred on to return to Kojima Productions to have 'discussions' with staff. Infer from that what you will.