I don't mean that Matsuno's absence means we'll never see Ivalice again. I just don't believe we'll ever get any solid answers as to how the series is supposed to fit together as a whole. I expect that future Ivalice titles will make vague, insubstatial references to the other games, but I don't expect any new information that'll help us connect the series. I believe that Ivalice, as continuous world, died when Matsuno left, unless he's divulged information regarding the continuity to others.

Also, regarding the Ivalice Alliance, look at the games it has produced. FFXII:RW, FFA2, and the FFT remake. FFA2, as a sequel to advanced, can again be written off as not the real Ivalice (at least, as far as I know; I've not enough interest to actually look into it); the FFT remake is just that--a remake--and offers little new in the way of revelations about the world; FFXII:RW is the direct sequel to FFXII, and, from what I understand about the title, offers little new information that would help bridge any of the gaps. I expect future Ivalice titles to be much the same.