You have put a great deal of effort into this library and I would like to see the chances of acceptance during the review not hindered by non-essential choices. The bottom line is that implementations in the boost::afio namespace will have different scrutiny than automatic promotion to the boost namespace. Start with these concepts in the boost::afio namespace and then at a later date, request a review to promote them to the boost namespace as full-fledged libraries.
I don't think it is worth risking the review outcome on trying to get multiple libraries into the boost namespace.
+1. And let's not forget there is precedence for all this, in fact it's actually not uncommon for folks to say "this is too much all at once, lets review the core part X, and leave everything else as an internal detail for now". There are also multiple possible outcomes other than accept or not - again it is not uncommon to the consensus to be either *Accept, conditional on changes. * Accept, conditional on major changes and a further mini-review. And finally.... there is no good time to go to review, most libraries are never really "finished" as such, at some point the library author and review manager have to decide that it's close enough to get detailed feedback. Of course reviewers are free to disagree on this. Best, John.