Maximilian Dood
speculates in this video from 16:10 to 18:46 that the Yuffie DLC will show her character going through trauma and failure which in turn will make her more brash and aggressive for when she joins up with Cloud & team. Max is arguing that the way Yuffie acts in the DLC is not in line with her 'OG self' and that the events will turn Yuffie into 'the character that we know from OG'.
I'm typically in the camp that I don't think the main characters of FFVII are dramatically different in OG compared to how they are in the Compilation. The Yuffie presented to us in this DLC feels the same to me as the one presented in OG and Compilation, with only the precise stakes in the story being different. Max does make me ponder though on an aspect about Yuffie that the original game never had to deal with: Yuffie's thoughts and plans while she was with Cloud & team before going ahead with stealing their materia.
If Yuffie joins you early in OG it's conceivable that there were countless moments when Yuffie could have stolen your materia. She clearly joins your party with the intent to steal but it takes a pretty gosh darn long time before she actually goes through with it. With how detailed and thought-out the character writing in Remake is, I don't think they're going to leave this part blank. We will see Yuffie struggling with her allegiance, actually becoming cozy with Cloud & team and perhaps choosing not to steal their materia at a time when she technically could. Then something Wutai-related will happen and Yuffie feels that her hand is forced and she ends up stealing the materia.
Another part that the original game never had to deal with was the LOGIC of the party accepting Yuffie into their ranks. It makes absolutely no sense in the OG for them to accept her, especially if you fell victim to one of her tricks even a single time. Remake Yuffie will actually need to have a compelling reason and a good argument for why the team should take her under their wing, otherwise there will be no way to accept the scenario in a game like Remake.
One idea suggested in the "hopes for story" thread is that maybe Yuffie will guide the team across the Midgar Zolom marshes, though even after that scenario where Yuffie helps she will need to explain with the team why she wants to continue on the journey with them.
So even if Yuffie becomes "brash and aggressive" (as Max puts it) by the time she joins Cloud, I believe she will quickly develop friendship with them and that this is what postpones her decision to steal their materia.