Taking the liberty to repeat the following question from May 3 since it
went unanswered so far: (updated and rephrased a bit)

The relationship of Bibframe to RDA and MARC appears to be very
cloudy, at least to those not involved in the actual development.
Some uneasiness here comes from the fact that the implementation of RDA
was to be tied in with "credible progress" being made toward a
successor for MARC21. Two questions:

A. Can Bibframe honestly already be called credible progress in
    that sense, because "MARC21" means a lot more than just
    an abstract data model: if means a format and a communication
    medium and a language [in fact the lingua franca of cataloging
    the world over] that actually works and up until now is an
    integral part of the global bibliographic infrastructure.

B. May it not just be that Bibframe turns out to model bibliographic
    data in a very up-to-date way but that this new way diverges
    a bit much from RDA logic and essence and thus will not
    accomodate RDA data easily or reveal RDA as old-fashioned
    and deficient as it is?

I'm not saying a successor to MARC21 is unnecessary or impossible.
But does it not appear that "credible progress" might take a bit
longer before it can be called credible or progress? In my
understanding, perhaps too old-fashioned, that would include
large-scale demonstration of both the input and editing aspects
as well as the data communication techniques and search