I'm fairly certain that Nagoya-Komaki is going to convert to a GA
/Bizjet/military airfield once the new Chubu-Centrair facility is ready for business. It's surrounded by development (much like Osaka-Itami) and offers no opportunity for expansion.
I doubt the Japanese government will repeat the same costly mistake they made in Osaka ten years ago... splitting domestic and international traffic. The situation at Itami was relieved considerably, but traffic through Kansai has remained relatively slow (can anyone tell me WHY they're building the second phase?) I'd look for Chubu-Centrair to open with ALL
Nagoya air traffic. Nagoya isn't as large of a travel market as Osaka, and splitting the traffic could lead to a Montreal-type situation - two underutilized airports.
Chubu-Centrair is also built in much shallower water than Kansai, which (hopefully) means they won't have the settling and 'sinking' problems that have tarnished KIX
I've heard very little about the new Kobe airport. How long will its runway be? Will it be able to handle widebody shuttles from Haneda? If so, I'd look for Itami and Kansai's traffic to fall off even more.