Thats just it. The end of 7R has already shown they are adding whole new plots.
The end of VIIR introduced new plots, yes, but the whole of VIIR was not new plots. Your suggestion is basically that they pull a complete-ish narrative of comparable size and content to VIIR out of much less pre-existing material while simultaneously saving those already newly introduced plot points from the end of VIIR until the next game.
I won't say it absolutely won't happen, but I'll reimburse you your expenses for VIIR-2 if it does.
The period between Kalm and the cargo ship in the original game is largely narrative downtime. It's such a lull in the acceleration of the narrative that you run into the Turks and they do not even fight you because they, like the story, have moved on to Sephiroth for the time being. And it happens in a location you never visit again -- one of several such locations that fill this period in the narrative.
For the most part, the trek across the eastern continent just establishes a handful of small world-building elements that won't become relevant until significantly later while featuring as much or more that is rudimentary to an RPG and forgotten as soon as you move on.
So, to summarize and reiterate: the design choice you describe strikes me as infinitesimally unlikely, even for Nomura and co. It would amount to attempting to stretch a segment of game time that typically takes three hours into more than 30, and would actually be a massive departure from what was done with the first installment. Which, yes, stretched a segment of game time that typically takes about 6 hours into more than 30, yet did so while utilizing a portion of the game that also comprises about a quarter of the original script (I checked) rather than at most 1/8 -- accumulating even that much only by virtue of the very beginning and endmost corresponding segments in the original game.
Long story short (too late, I realize this), even if the fanbase cared enough about that segment of the original game to accept such a decompressed milking of the story, I don't expect for one second that the developers care enough about it to spend that long with it.
