Today I emerged the following versions of gwenview and digikam with libkipi without problems:
kde-apps/gwenview-16.04.49.9999:5
media-gfx/digikam-9999:5
media-plugins/kipi-plugins-9999:5
kde-apps/libkipi-16.04.49.9999:5/31
All these ebuilds are available in the kde overlay. Bear in mind that that ...