I just rediscovered this reply from Vetex stating that more Spirit Rites will be added “next update.” So it seems like the rest of the Eagle Patrimony Rites are intended for the Empires Update after all, rather than Full Release.
I doubt 5 Rites will be enough for Vetex to unlock Oracle, though. Warrior released with about 36 skills. But then again, they could only use about 6 of those at a time, so maybe Oracle and Warrior are close enough in that regard. Also, Mage and Berserker released with only 7 skill types, so… Maybe 5 is enough for Oracle?