Quote from Nomura & Kitase about how many parts the #FF7R will be (slight spoilers):
Nomura: We wanted to have the last boss fight take place at the highway in Midgar, which arises questions that I cannot answer. There is a character who’s alive, which leads to a great mystery.
Kitase: (How many parts?) We have a general idea of how the story will play out, but we haven't decided exactly [how many parts], nor can we confirm anything. There's speculation that it will be 3 parts, but we're just doing things one step at a time.
Nomura: (How about the next part?) Depends on how many parts the overall story will be. If we divide the story into large parts, it'll take longer to make. If we divide it into more detailed smaller sections, then developing it will be faster. I hope to release the next one ASAP.
Basically Nomura is saying that if they focus on shorter stories within the overall story (let's say, focusing entirely on Junon alone as a crazy idea), it'll be much faster to develop as opposed to taking the OG story in big chunks and developing those as whole installments.