I actually wouldn't be so sure this is the last one. Hal has been saying this may be the last one since V-Saikyo 2 because he's always anticipating that the heat death of the game is always around the corner, but it insofar hasn't happened (even if it's clearly not in stellar shape. Indie Devs pls understand).
There's also a discussion to be had about sponsorships and projections. CR Cup has already had a Valorant and OW2 tournament and both of them performed worse in overall viewership than Apex. This is mostly due to the format of a staggered 5v5 league table rather than 60-man multi-POV, as well as there being less places available because OW2 only has 4x teams of 5, and Valorant 8x teams of 5.
For them, that's fine, as Crazy Raccoon are their own enterprise run by pros of all three games, but Hal is not. Hal is an Indie who shoulders the responsibility of his own V-Tuber corpo now, and so the decision to host a new tournament at the expense of Apex is far more precarious for his bottom line. There will always be more people willing to join the Apex format, and it will always result in more viewers which, in turn, leads to more eyes on the merch he's trying to sell. This is mostly coming out of his own pocket.
Maybe he will post a tweet in 10 minutes saying it is indeed the last one, but there's also other factors. For starters, TSB don't have to reunite specifically under V-Saikyo. This tournament introduced big content creators like Nocturnal and NiceWigg to the community, and both RPR and Selen herself have been tossing around the idea of hosting their own EN format for a good while now.
As for her status as a 9x Top 500 player in Overwatch, that's certainly true, but also consider that the only Japanese players that even give a shit about that game are usually the ones who are really good at it, so the standard of entry for that tournament will be much higher. Hal can't very well slice the participants by 66% and also try to maintain the same mid-core player skill and expect the same level of interest in his product.
Even if Apex as a game is in a sorry state, Apex as an opportunity to bring lots of people together and host something huge is still probably the most lucrative game in the genre.
Valorant will also almost completely shut down any overseas participation due to high ping and the Valorant pros not being connected to the V-Tubers in Japan, so Hal loses out on potential growth there too. They'll never fit all of VSPO in those teams, Nijisanji representation will be way down. Hololive and Holostars likely won't see any participation whatsoever because even good players like Astel won't get in over bigger creators like VSPO, Kuzuha, Kanae, Lauren etc. Smaller creators like Shishigami Leona and Hira Hikari will just never get a chance and the tournaments will homogenise into the same relatively small clique of tryhards that CR Cup operates in.
I think Hal will at least continue for 1-2 more, and if he doesn't, I feel like someone else like rpr will see it as an opportunity to jump in and host their own, and TSB can just go there.