I think there will be a more open world/roadtrip theme sorta like XV because:
* From a marketing POV, or just a cohesion POV, they need something to set each game apart from the previous one, tie it together, and give people something to be excited about. It can't just be "here's a random collection of locations and events you might remember from the original FF7 and some random new stuff, kthxbye, see you next time". They want each installment to be treated like a brand new numbered FF, which probably means not only new story elements but also new game systems, etc. For the second game an overworld is a good vehicle for this.
* The most important reason

: Nomura is evidently using the FF7 remake (and apparently KH4 lol) as a way to revisit ideas from his version of FFversus13. The road trip/overworld aspect of FFXV was a carryover from the original Versus concepts, and in fact it was envisioned as a modern version of the "road trip chasing Sephiroth" section from FF7 which was originally Nomura's idea BTW, so here's his chance to give us his take on the road trip concept and show us how he'd have done it better than Tabata did.
