Since Killua and Gon have been separated for a year now in the manga, and there’s no indication they reunited, do you think Killua might have left with no intention of reuniting and traveling with Gon again? It seems sad that one mistake dismantled all the good Gon did for Killua in Killua’s mind :(
well, first of all i’m not too worried about the passage of time in the manga because hunter x hunter in this regard is like an old greek epic. when togashi leaves some characters to focus on others, the narrative time stops for the former. which is somewhat silly, but charming, i guess… in an absent-minded, i-do-not-remember-the-milestones-of-the-timeline-in-my-own-story way. my speculation that it might take killua and gon no more than a year to come to their senses and work things through is just that - a speculation. togashi doesn’t put much stock into the ‘time heals’ concept; he appears much more proactive when it comes to resolving the conflicts that his characters face.
so no, i do not think that this is it for killua and gon, both because it seems rather unlikely for togashi to leave that plotline hanging (it’s the central unresolved conflict of the ca arc), and because of the nature of gon and killua’s relationship. people of their age meet and separate without ever looking back all the time, but killua and gon went through a number of formative, life-changing experiences together. try as they might, they won’t be able to just up and cut all ties with each other.
i do not think that killua wants to leave gon behind for good, either. he seems to realize that he needs some distance from gon, because he’s been putting his friend on the pedestal and shaping his entire existence around him for way too long. i think he knows that he needs some time to learn who killua is without gon, and frankly, it’s a healthy thing to do in my opinion.
and last but not least, for killua leaving with no intention to reunite and patch things up with gon would be a strange narrative choice to say the least, considering how much foreshadowing that scene under the world tree contained, both from the symbolic point of view (parting under the world tree, a mythical representation of the center of the world, where everything begins and ends, something people keep coming back to), and from the point of possible character development for alluka (she says that she’ll “return” killua to gon, implying that she will soon be independent enough not to need killua’s protection, and i like to think that she might even play a major role in killua’s development as a character, making him reevaluate his relationship with gon and come back to it with a healthier approach).