I agree with You on the general idea but I have to disagree on some of the points you provided.
let’s all first agree on the fact that Oda is not successfully presenting the female characters, especially a Yonko, Big mom and one of her sweet commanders (smoothie) who IMO was the biggest disappointment in the WC arc and in OP in total.
but if we compare male and female characters, Oda does make some male characters who are supposedly strong into some kinda joke sometimes.... I mean look at queen
the difference here is that out of 3 or 4 Male characters, one dude falls out of expectations, while the rates are much higher for female characters, sometimes we get 1 good female character out of 4 or 5.
Has oda been inconsistent since the beginning of the series regarding female characters powers? Yes IMO.
Is fan service a part of why Oda is showing female characters this way? Yes.
is it working (the fan service)? Yes.
Do I expect it to continue? Yes (anything works will continue, trust me)
Now, about Bonney, I don’t think Oda put her outta the picture, I think her time is yet to come, but if Oda really did Role her out, I would be very disappointed.