It is oftentimes alleged by those who affirm the Nicene understanding of eternal generation that its denial logically needs to tritheism. The reason for this is because each Person of the Trinity is represented as a separate being, rather than the Son being seen as proceeding from the Father eternally, and the Spirit being seen as proceeding from the Father and the Son (or, if you are Eastern Orthodox, only the Father) eternally(The Eastern Orthodox condemn those as affirming the filioque as adhering to a kind of modalism).
I argue, however, that affirming the Nicene understanding of Christ's eternal generation of the Father in no way circumvents traditional charges of tritheism. The very fact that neither Person of the Trinity is reducible to any other is precisely why we are (erroneously) charged with tritheism, regardless of one's understanding of the procession of one Person from another. It ought to be sufficient that we affirm that there are three Persons of the Trinity, each irreducible to the other, and that each one is fully God, and that we nonetheless believe that God is one and that there is one God.