There was some discussion in an earlier thread about the question of which agency usurps NijiEN's place in the #2 EN spot, and I have a thought or two that I had and thought I might spin off into a new discussion:
First off, I feel like we're underrating how arguably HoloEN was in the #2 spot until Advent, at least by some metrics. Using the VStats monthly summaries and I graphed LiveEN+StarsEN's total monthly watch hours against NijiEN's, and as you can see, in the 11 months between records beginning in September 2022 and Advent's debut at the end of August, Niji was ahead in watch hours – occasionally quite substantially – for 10 of those months. Granted, the watch hours per member would have been a good deal lower for Niji, but for a lot of purposes, it is overall, not average, viewership, that will count. And note that this isn't including B2 views which would add a bit more to NijiEN.
To add some more context, comparing HoloEN and NijiEN CCV between May 2022 and 2023, there's a huge year-on-year drop for everyone except Fauna, even if Niji in particular was hit much harder. How you also interpret the data from the previous graph is up to you, but it suggests that NijiEN viewership was a lot stronger than HoloEN for most if not all of 2022 (yes, I am saying Fulgur was technically right), but then declined at a more substantial rate amid a more general downward trend for both. HoloEN really only decisively regained the top spot because of Advent, which I think really puts the effect of their debut into much stronger context.
The other thought I had, though, relates to the above. The fact is that with NijiEN already dropping well behind HoloEN and continuing to decline, becoming 2nd place is not really indicative of much. Being 2nd place just means being 2nd place. Getting to 2022 NijiEN levels of popularity is its own distinct challenge, and one that I honestly no longer think the current industry landscape can allow. Disillusioned Niji viewers are not going to just migrate en bloc to one new contender; they're going to be a heterogeneous mix of people, some of whom will quit VTuber viewing altogether, others of whom will find their viewing niches again in any number of the literal dozens of small EN agencies or hundreds of indies out there. No single group has managed to sustain the level of group-wide (as opposed to single-member) hype necessary to decisively carve out that kind of spot, and I'm increasingly unconvinced that none of them ever will.