My 2 cents. Everything that has been in these "side" stories has had something happen where something needed healing or mending (IE: Terra, Aqua, Ven, Xion, Org 13, etc). So maybe the other "secret project" will be Re:Connect. Maybe Kingdom Hearts its self needs healing, it is the "heart of all worlds" and last time I checked it was it pretty bad shape. I'm not sure, just thinking something along the lines of "Cleaning up KH saga 1."