I think Feitan and Phinks are not immediately at risk of dying? Lol. That could be just my denial though, but they have decent development among the PT members. 

Feitan is a character I think in particular is built up for some kind of development, given that he is used to show the strength of the Troupe to Kalluto. He’s my favorite troupe member after Illumi, Chrollo, Kalluto, and Machi. His perspective is seemingly very along the lines of loyalty to an ideology no matter the cost, as is shown in how he wants to fight Kurapika at the risk of Chrollo’s death in Yorknew.

Phinks is similar to Feitan, but Phinks is more obviously emotional whereas Feitan is calculating, and therefore they balance each other out well kind of in the same way Leorio and Kurapika do where one is analytical and the other is more hot-headed. But he is also, like Feitan, more loyal to an ideology than a person when it comes to the Spiders. Like he won’t even help Feitan during his fight with Zazan because rules. 

Both Phinks and Feitan, though, do show some kind of sadness after Paku’s death, Phinks especially. So they’re not like care-less monsters; on the contrary, I do think they care deeply about the Troupe members, but they care specifically because they’re members of the Troupe, because they care about the Troupe and its purpose. That’s why they came into conflict with Nobunaga and Machi during the Yorknew debate, since they seem to care more about the individuals in the Troupe. 

Anyways. I hope they both get a bit more development before/if they die, especially if this whole ideology vs people issue is revisited.