Victoria taking the narrating role doesn't mean anything other than her taking the narrating role. IMO
Don't forget that Emily lost plenty of battles despite her narrating the past 3 seasons. Victoria is up for her fair share of losses too. This doesn't in any way guarantee that Victoria will succeed. Like YR said, it's just a switch up to try and create hype for the show again and freshen it up. The whole "reincarnation" is hype talk that you can only expect from a producer, right? It won't really change the WHOLE dynamic of the show, it's still Emily vs Victoria as it always were judging by what we've heard, tbh.
What I like about this season from what I hear is that it's may be focusing on VICTORIA vs EMILY with no distractions (well, hopefully). Last season was great for the first half and then lost it's way with lots of filler and trashy storylines with Margeux (or w/e ha name is), it completely ruined the build up for what I felt should've lead prior to Emily's identity being exposed. There wasn't really any good anticipation, it just happened in the last few seconds of the finale and it was quite tragic execution as it was the only good few seconds of a season finale (which isn't good as Revenge usually slays in that aspect).
I hope the pacing and storywriting is done great this time and Emily and Victoria have some properly IN CHARACTER epic moments!
Also, bring Mike Kelly back for season finales. The new guy can't do **** with them after that season 3 finale.