(My apologies for the very late response; the core team discussed this proposal in mid-January)
The public review of SE-0010 “Add StaticString.UnicodeScalarView” ran from January 6...8, 2016. The proposal has been rejected.
While the addition of StaticString.UnicodeScalarView is a useful feature by itself, the core team felt that it would be inconsistent just to add this narrow set of APIs for Unicode scalars. StaticString itself is a bit odd: it’s UTF-8 API works differently from String, there is no provision for UTF-16/32, etc. If StaticString is to gain Unicode support, it should be done comprehensively, not piecemeal. Moreover, with the aforementioned String re-evaluation underway, it is possible that StaticString itself might change considerably or even be obsoleted.