@Kaptayn:
All your judgment is biased because you're going with this wrong assumption.
Hisoka and Gon will never fight. Edit: using this argument would be like claiming that Chrollo can't die because Kurapika has sworn to kill him.
Chrollo is a more minor character when compared to Hisoka. Chrollo was setup later on in the story, and was the main focus of an entire arc where he was essentially defeated anyways. Hisoka not only has a much longer running story theme behind him (to watch Gon's growth throughout the series), but he's also had a much stronger vibe of holding back throughout the series. There's much more story and intrigue in regards to Hisoka at this point than there is to Chrollo. To put it more simply:
1.) Hisoka was a fixture at the beginning of the series and has more intrigue / untold story.
2.) Chrollo survived York New, but having him be a main fixture again after essentially being defeated would be boring
3.) Because of plot elements in his favor, it's highly likely that Hisoka has a good set of plot armor in this fight.
4.) If Hisoka has plot armor, then he's holding something back and our understanding of this fight so far is probably wrong.
5.) Hisoka wins this fight in the end. Or at a minimum it's a draw where both live on for another day.
It's always possible that this is wrong and Togashi just decided he was bored of Hisoka. However, it seems way more likely that Hisoka is going to power through this via an unseen method and live on within the HxH verse.