I dunno. People greatly overestimate the amount of content left for Disc 1. If they remade the entire remaining content of Disc 1 as linear hubs this is what we get using the original map as a basis.
I can see them adding a few places like Healin Lodge and maybe some extra small settlements and dungeons for sidequest purposes, but there's no reason they couldn't make this area play able at a decent scale.
In terms of chapters you basically have:
- Kalm to Mythril Cave
- Junon.
- Costa Del Sol to North Correl
- Gold Saucer
- Cosmo Canyon
- Nibelheim and Mt Nibel
- Rocket Town
- Gold Saucer Revisited
- Temple of the Ancients
- City of the Ancients
Gongaga was option in the original but they'll probably make it mandatory
After you defeat Weiss it very strongly implies that Weiss was actually Hojo testing out uploading his mind to VR and using Weiss' form.