How sound is the Hadith, "Islam began as a stranger and will return as a stranger, so blessed are the strangers," and what does it mean?

The aforementioned Hadith is authentic, narrated as a Marfu' Hadith (a Hadith directly attributed to the Prophet, peace be upon him) through several Companions, including Abu Hurairah, Ibn Mas'ud, Sa'd ibn Abi Waqqas, Anas ibn Malik, Sahl ibn Sa'd al-Sa'idi, and Ibn Abbas. The meaning of the Hadith is that Islam began as something strange due to the scarcity of its followers and the hostility of the polytheists towards it. It will return to being strange at the end of time due to the scarcity of those who adhere to it, despite the large number of those who claim to be associated with it. The description given for these "strangers" (Ghuraba') is that they are "those who rectify when people become corrupt." "Tuba" (طوبى) means Paradise or a great tree therein.