We wouldn't expect Final Fantasy VII Remake to be a beat-for-beat rerun of the original; the graphical overhaul alone is going to significantly alter locations and the feel. But Square-Enix has hinted at further changes.
"We haven't shown any gameplay yet, but since we're updating them quite a bit," stated Tetsuya Nomura in a Famitsu interview (via Kotaku), though he did acknowledge the original's game systems are a big part of of what makes FFVII.
"Since we now formally revealed Kazushige Nojima's name for the scenario, there will be more plot devices in the story," he continued, suggesting there will be some alterations - whether tweaks or complete changes - to the original story. Something that he believes is needed, not just to avoid having two versions of the game on the one machine (despite the differences), but also that fact that "if you are going to do a full remake, you have to take a different approach and make something that suits the times."