I think it is in reference to the return of idolatry in what is now known in Saudi Araba, where they will start to worship the idols of Jahalliya.
(English translation of Al-Bukhari: Volume 9, Book 88, Number 232: Narrated Abu Huraira: Allah's Apostle said, "The Hour will not be established till the buttocks of the women of the tribe of Daus move while going round Dhi-al-Khalasa." Dhi-al-Khalasa was the idol of the Daus tribe which they used to worship in the Pre Islamic Period of ignorance.)
Grandpa there could be a general fear for his ummah, and then a specific fear for a certain group at a certain time.
Also, I because of your ignorance you have labeled the hadith where it is stated that the ummah will not worship idols as weak when it is saxiix
Bukhari Volume 5, Book 59 [al maghazi - the battles], Number 374:
Narrated Uqba bin Amir:
Allah's Apostle offered the funeral prayers of the martyrs of Uhud eight years after (their death), as if bidding farewell to the living and the dead, then he ascended the pulpit and said, "I am your predecessor before you, and I am a witness on you, and your promised place to meet me will be Al-Haud (i.e. the Tank) (on the Day of Resurrection), and I am (now) looking at it from this place of mine. I am not afraid that you will worship others besides Allah, but I am afraid that worldly life will tempt you and cause you to compete with each other for it." That was the last look which I cast on Allah's Apostle.
Also, one can join the Mushrikeen as in an alliance against other muslims, but not mean become a mushrik. Think why the rasul scw distinguished "joining the mushrikiin, and tribes becoming mushrikeen. "