I've heard about parts of those Utimania interviews, apparently conducted as recently as March, where key members of the remake team indicate that they aren't sure how - or if - the next part is going to handle the original game's open-world sections. One of them admits that he doesn't remember how that part of the original actually unfolds, and says he'll have to watch a play-through. If they had no clear idea of what they were doing only two months ago, then that doesn't offer much hope.

"Staying true to the original story" describes most of the first installment of the remake, but its ending seems to make it basically impossible for them to follow the original any further. The 'arbiters of fate' were trying to presevere history, and showed the heroes glimpses of what was "meant" to happen - including key scenes from throughout the original game. The whole point of the remake's ending is that the heroes now know what fate had in store, but they've fought against that and are going to make a new future for themselves. The "unknown journey", or however it's described in the final blurb. To me, that felt like an admission from the writers that they simply can't or won't try to retell the original story, so it'll be fanfic from here on out.

Other than that, the remake was doing pretty well until Sephiroth used his sword to open a time portal by chopping a hole in reality, unleashing a sequence of pure Kingdom Hearts bulltrout of the highest order. Then again, things were already getting dubious when magic invisible time ghosts started intervening in events to prevent characters from learning too much or too little, or to ensure they got injured or stayed alive at the 'right' time.