that article is 2 years old, allot has changed. Dungeon hero is on hold and SH3 is now a reality instead of just words.
It would be a safe bet looking back on FF's history that the new 3D engine will be used to create SHC2 after SH3. You're not going to spend allot of time making a new engine only to put it down after 1 game.
My theory is if sales on SH3 are positive SHC2 will follow soon after, they will not be released at the same time.