Something is likely lost in translation. ReFS is not a super set of NTFS. That would be stop the press front page news.
What is more likely is they bringing over Windows Server Storage Spaces, that is, deduplication and those kinds of services. You already have access to ReFS right now on Win 10 Pro. (this was already possible by copying bits from matching server build, though every new build you might lose access to your storage pools unless you again brought over binaries..)
Hopefully this includes more advanced Hyper-V features like direct device(GPU, PCI-e) pass through.
edit: to be clear, there hasnt even been rumor of ReFS boot support for long time. They are still co-equal/separate filesystems for different priorities.
What I learned after 30 minutes with ReFS
There is no support for NTFS features like per-file compression nor encryption. Full disk encryption with BitLocker seems to be supported, but I haven’t verified that.
Windows Search worked fine even with advanced queries.
Windows Backup (a.k.a. File History) will let you backup to and from a ReFS formatted disk. This is probably a bad idea, however, as File History relies on a lot of NTFS features.
Windows Store can’t install any Windows Apps to an ReFS formatted disk. It’s listed as an available installation destination, but the Store app will thrown an exception if you try to install to it. ReFS doesn’t implement the necessary parts of NTFS’ access control entries required to enforce Windows Store’s app licensing technology.
I installed a couple of programs to an ReFS formatted disk, and most failed to start.
All programs I tried could open and save changes to existing files to an ReFS formatted disk. However, about half of them had problems creating new files.
I got a steady 70 MB/s when copying a large number of small files onto a ReFS formatted disk. I got speeds varying from 150–180 MB/s with the same file set when copying it to the same disk formatted as NTFS.
This is same issues i ran into, the compression and the much slower copies(vs copying to same disks under mirrored ZFS volume). Of course things like de-duplication and using same exact binaries as Server would be a big win.