56.1 is available now (and presumably stable). Chromium would very much like to use the newer features in 56, I was able to conditionalize them out, but Google is cherry-picking changes in 56 and backporting them to their 54.1 bundled copy of icu... so this is likely to eventually be a problem. Hence, the request to add 56.1 to rawhide sooner rather than later. :)
I'll try to upgrade next week. However, I'll first test 56.1 locally with LibreOffice so we don't run into surprises..
Waiting for side tag to be created, https://fedorahosted.org/rel-eng/ticket/6281
Builds of dependencies ongoing on f24-icu side tag.