One key, but complex, concept in Childs’ integration of h-c with a
study of the "final form" into what is claimed to be a post-critical
approach, is "canonical shaping". But, back a step, for
Childs canon is not only a fixed and final list, but also a process.
During the time that tradition, redaction, source and form critics
claim to uncover, the text was on its way to becoming canon. The
redactors et al. who passed the text on from generation to generation
did so because it was (in a sense) Scripture (even while it was still
oral;). This pre-history of the text shaped it and its meaning. This
shaping therefore to some extent defines what the canonical text meant.

So, if Hosea and Amos did (as redaction criticism says they did)
undergo an editing to reapply the prophets’ words to Judah (addition of
mentions of Judah, David etc.), then this shaping is part of what the
texct means as canon. Therefore the canonical prophets are ipso facto ripe for reapplication in similar ways in future times…

 Hope this is clear, but it is a complex idea!