One more difficulty, assuming something like the “make change, then ping maintainers to fix resulting breakage” approach: Many packages have no formal maintainer. We need to decide who is responsible. One approach would be to go down the graph to the nearest maintained dependency(s).
If you want further input, there is a lot of interesting discussion (including this point) in PLEASE fix ALL packages which were broken by the Qt-wrapping-changes. Its a long thread though.