I think Hisoka will live!
1st: The author made the storyline so inclined to Hisoka ultimately fighting Gon, i mean it is his choice to change the storyline whenever, but given the preexposed hints and whatnot, I believe Hisoka will live somehow.
2nd: As for his torn off hand and leg, I think if anything, since Machi favours and follows Chrollo, she will definitely NOT cure him with her needles (but i believe his limbs were exploded anyways)
3rd: I think if anything this would be how the author would bring Hisoka back with Killua/Gon, where he would eventually get Alluka to heal him again, thus bringing the three back together.