Although some of what you said is true, but as far as those three being overpowered in one-on-one fights, you do realize that this was a similar argument against Jinbe. Mostly pre-timeskip, of course, but even in the weeks leading up to the Fishman fights, there were people who still thought that Jinbe's power disrupted a dynamic of the Strawhats.
And regarding on how to use basic logic, this is especially easy to say if you are the supporter of the theory that turns out to be correct. While there are ridiculous forms of logic people will use to argue for(or against) a potential future crewmate, it is only logical at a certain point in the story. Oda is the storyteller, so he is creating the logic of what happens. If someone had told this forum several years ago about half the things that happen in this manga(like Blackbeard getting two fruits), they would get laughed at, and the other members would be calling on that person to be banned for trolling. I suppose I'm saying that knocking the supporters of other characters at this point seems like an incredibly haughty thing to do when it doesn't matter anymore for those characters now.
Pantheras is right, at least to a certain degree. Well thought out theories of what might happen in the future in One Piece are, at least for me, always appreciated. I remember a post( at that time i was just a silent reader of the forum) i think by brennen.exe two and a half years ago in which he showed his theory of Jinbe joining. At that point, most of the forum members laughed at that theory but just look at what happens now. There were also very good theories about Hancock joining btw but that obviously didn´t happen. I also have to say though that there are people who just declare that a character will join just because he/she has a nice style or because a character is a girl and that´s what the SH need. That´s obviously plain stupid and has no constructive value for a discussion in the forum.
So concerning Bonney, i think she will play a huge role in one of the upcoming arcs where she could be a candidate for joining. Reasons:
1.) It seems like she has some kind of relation to either WB or Ace (which i would prefer actually) because she was crying when WB was accused of betraying his comrades.
2.) She swore after the war to find the one responsible for WB and Ace´s death in the New World and then we see her after having lost to BB (where he claims btw, that she doesn´t deserve a bounty of over 100mil, this could also be a good plotline if she would join SH and then fight again against the Blackbeard Pirates).
3.) She has some kind of connection to the Government (because of what Akainu said), be it as a slave maybe or even a noble.
4.) She is one of the few Supernova who had a direct interaction with one of the Strawhats (Zoro), though i have to admit it was pretty short.
5.) She also swore at Sabaody to find the SH and fight them because it was their fault that an Admiral came to the island.
At this point, i really could imagine a scenario where Bonney is on the run(without her crew obviously) and requires help and the SH,like many times, agrees to help her which would be actually quite ironic because Bonney was the one who said that pirates aren´t people who go and help people randomly.
