Grammar Question: Remain vs. Remains

The focus of the sentence may be Company XYZ, but the grammatical subject of the sentence is “the few true partnerships” - unless the author is trying to say that only Company XYZ and no others of “the few true partnerships” remain (etc., etc.). But if that’s what s/he is trying to say, why mention any others at all? By definition, Company XYZ would be unique in remaining a true partnership in the banking world.