I think the concern is that the writing may be on the wall for (the current memory-unsafe version of) Coreutils. Despite the bugs and incompatibilities, Canonical seems to have decided that the memory safety of uutils is worth it. And those two downsides, the bugs and incompatibilities, will likely attenuate quickly, compelling the other distros to follow suit in adopting uutils before long.

So the continued popularity of Coreutils might, I think, depend on Coreutil's near-term publicly announced and actual memory safety strategy. As I suggested in my other comment, there are (somewhat nascent) options for memory safety that do not require a rewrite of the code base. (For linux x86_64 platforms, depending on your requirements, that might include the "fanatically compatible" Fil-C.) And given the high profile of Coreutils, there are likely people willing to work with the Coreutils team to help in the deployment of those memory safety options.