All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
The mentioned Hadeeth of Abu Sa‘eed Al-Khudri is one of the signs of the Prophethood of the Prophet Muhammad, sallallaahu ‘alayhi wa sallam, wherein he relates the state of most of the Muslims who would follow the ways of non-believers and imitate the People of the Book - Jews and Christians - who were specifically mentioned in other wordings of the Hadeeth in question.
The Hadeeth is intended to clarify the prohibition on following them or turning to non-Islamic law, since the Sharee‘ah of Islam abrogated all other laws.
It is a Muslim’s duty to adhere to the laws of Allaah, follow the way of the believers, steer clear of imitating disbelievers, declare his allegiance to Islam and deny disbelief and those who follow it.
Allaah Knows best.