I can see it now:
Togashi has this planned out as the introduction of a whole new level of HXH storytelling. Thought Nen was the extent of this series? Well, you thought wrong. With Alluka, we´re shown the first touching of inter-dimensional travelling. No hunter has ever traveresed these dimensions, but with Netero dead and the Zodiacs playing annoying political games, the world of hunters stagnated. Born from this stagnation is an all encompassing motivation to experience the beginning of your hunter life. This marks the start of hundreds of highly skilled hunters to cross dimensions, trying to explore new realities.
That is what all the events up to now prepared for. We´re a third in. Two thirds of HXH remaining. Togashi found a way to live to age 250. :|