Here are my (admittedly somewhat optimistic) thoughts about HxH will proceed.
First of all, we need to ask ourselves why the Kakin arc happened. After all: Togashi is a man with lots of plot to tell and little time. The DC is a huge place, so why waste more than 32 (and counting) chapters on something that seems like a side story (they boarded the ship on chapter 358)?
There are two possible reasons i can see.
Either Togashi intends never to go to the DC for real and wants to focus on kurapika, the spider and the zodiac on the black whale and end the manga on the new continent with the dark continent being what they go to in the last chapter.
That would make some sense, but admittedly, i dont hope that is true. It would be a valid writing choice, but after the DC hype up, a disappointing one.
The other reason would be to prime the reader into understanding the shift of the manga from battle shonen to more indirect fighting. Using an arc like that to get any spider and kurta eye content out of the way seems smart.
In that case however, the are going to be on the black whale for quite some more time (at least 30 chaps, mb more). After that, a DC arc (and a gyro arc) that would be worth the wait would in my opinion take (together) at least 200 chapters.
That means we'd be looking at an HxH that is between 600 and 650 chaps long. And i think that is where we are going.
200 chaps take togashi about 20 years, if he works slightly faster (15 a year) they'd take him about 16 years. That is very doable,
He'd be between 70 and 74 then, a lot of mangaka do work slowly until then and Togashi works slowly, he can take the pauses he needs.
To me, I see Kakin as a statement of 'this is just the prologue to what is to come' and togashi being sure he can do HxH until chapter 600+