Hmm, hard to say. Okita and Musashi might not be entirely viable in JP at the moment as ST Sabers anyway, but I think that's just because neither of them have ever had buffs, which is something they kind of need (and in Musashi's case I'd be shocked if she doesn't get one in the future given that she keeps showing up during the Lostbelts). Bride and Beni are weird cases, because they're offensive supports who can do a decent job as primary damage dealers, but most of the time their strongest role is using their skills to help someone else.
While Caesar is now much stronger than he used to be, and arguably one of the best ST Sabers thanks to this buff, keep in mind his gimmick is the same as Anne & Mary's, where he needs to have taken substantial damage in order to be the most effective. This is incredibly dangerous for two specific reasons:
- Caesar has no defensive skills whatsoever
- As a 3* Servant, without grails he caps out at level 70, and even with 3* Fous, his HP tops out at 10.5k
This makes using him in this fashion risky, because you have to build a team that allows him to get thoroughly damaged but not die in order to make the most of his NP buff, which is a lot of set up work that most of the other ST Sabers you mentioned do not need. You might be able to put out terrific damage if you succeed, but it's a play that might not be worth it given the level of difficulty of Lostbelt content, where I hear random crits abound that can just annihilate Servants (farming might be a different story, but why would you use a ST for farming anyway?). But Caesar's buff is nice for F2P and new players, who might not have that kind of firepower in the roster and could use someone with serious DPS to handle the latest content (especially because he's easy to max out his NP level), but does he destroy the tier lists of the ST Sabers entirely? I'm not convinced, and even if it did, DW's only one buff away from changing that ranking again.