i know this thread is dead, but i wanted to add my 2 cents!
the maria theory is interesting. the biggest hole in it imo is that it is canonically confirmed that haibara would be able to create an antidote if she had access to all of the drug's info. since the boss obviously DOES have access to the drug's info, it's pretty much impossible for them to be *forcibly* in the body of a child. unless an earlier form of the drug (maybe a version created close to the time vermouth took the drug?) both deaged the person and prevented them from aging.
we also have to think about gosho as a writer.
as in, i personally do not want the boss to be some rando. sure, i don't want it to be something crazy like prof agasa (i know he's been explicitly named as someone who isn't the boss, but just for the sake of an example), but i would want it to be a relatively prominent character with just enough dubiousness around them that the reveal would be like, "WAIT.... wait.... ohhhhh!!!!!!" that's what irks me the most about yoko/maria-esque theories; a background character as the boss just isn't narratively fulfilling imo.
BUT.... gosho seems to be fond of doing the whole random character route. he favors things like word play and subtle shadowing over a more broad narrative strength. so while the specific identity of maria comes off as somewhat absurd, i think the approach to the theory is actually very in line w gosho's approach to big reveals.
i do worry that karasuma is literally just gonna be karasuma LMAO. i mean, i don't think it's the likeliest option, but i feel like there's maybe a 10% chance that it'll just be like, "ah yes.... karasuma... he's been in hiding all these years...." lmao. or, like, genichirou kaneshiro
also, while i think there are a lot of holes in this theory, i find it really interesting: https://tetragon4-blog.tumblr.com/post/ ... f-ano-kata
the one thing i do agree with (or i guess think is most plausible?) in this theory is the fact that current anokata is NOT the original renya karasuma. it's not implausible for him to be the og one, but i just feel like the first karasuma died for some reason. the theory above outlines more specific reasons as to why op believes the original karasuma is dead, and they're interesting. it's mostly a feeling for me, though, lol. i also think it adds more flexibility as to possible boss identities without having to rely on the drug and gender and stuff - which i think is cool!
i also "feel like" (or, well, wld be a little dumb not to consider that) the miyano/akai family has GOTTA be somehow directly related to the boss. i don't think their involvement is just, like, a coincidence, or a result of recruitment that happened 30 years ago. it's more than that. i think they are somehow key to the whole puzzle/to the very origins of the bo. that's not far fetched at all. i saw a theory postulating that vermouth is mary & elena's sister, but, nah, i don't think so. she's just white. still.... idk.
it's also a little annoying because it's difficult to discern whether some connections are just a result of gosho wanting to add it for the sake of an easter egg/added drama or actually legitimate...
like, is there any larger significance to yukiko knowing vermouth, or is it just a "omg gasp! new york and stuff! also i can't believe my old bestie is a bad guy </3" moment??
what about the kuroba family? obviously, there's close to NO way they'll actually be involved in this whole thing, but, still.... toichi teaching vermouth? kaito's knowledge of everything & involvement in some bo moments? again, is this just an easter egg ("oh, so cool, the magician's dad taught the bad guy :O!!!! what coincidence xp!!!!") or is it, like, for real?
same with the kudos' weird knowledge of everything. is this supposed to be serious, or is this just a nice combo of a convenient plot point & proof that shinichi's parents are Good and Cool, After All?