I would plan on zero support since Microsoft only supports their server os and many desirable features are still
absent for this filesystem like quotas, bootable filesystem, removable media, encryption, etc...
It looks like Microsoft is adding a scrubbable and more resilient / thin provisioning layer similar to Apple’s successful transition APFS that completed on iOS several years ago and is basically complete on macOS now.
I would expose any ReFS data over a stable API like SMB or iSCSI rather than expect to read or interact directly with that flavor of storage from macOS.
All is not lost if Apple doesn't ship filesystem support as there are several user space filesystem extensions that have a long heritage of adding useful filesystems:
I don't see one for ReFS but I'm sure someone can write or show one once that happens and edit this portion of the answer to update it.