In class, Professor Webber postulated that the hunger artist is actually transformed, metamorphosized into the panther that occupies the cage after him. I don't buy this hypothesis because it implies Kafka's use of a "second-best" solution.
The panther's "joy" is purely instinctual, and is not based on self-determination. In contrast, the questions of the hunger artist were of a higher order. He was not looking for an ignorance that leads to bliss, but for knowledge. If, as it seems at the end, he does not gain this knowledge, it is highly improbable that Kafka would try to convince us that instinct is a suitable substitute.
In many of Kafka's stories, it is precisely the type of "higher order" questioning that fuels his characters. In some cases, they die unenlightened, and in others, they are allowed some revelation before their end. But never is a character knocked back down the evolutionary scale of self-consciousness. Even in the original "Metamorphosis," Gregor maintains his self-awareness; in actuality, he gains self-awareness through the limitations placed on him. But the panther's joy is not the joy that comes from knowledge, or the resolution of a problem, but rather from the absence of knowledge or problems to be resolved. It is a sort of lobotomization that Professor Webber is hinting at, a return to the idea of the "noble savage," and this idea is one that Kafka seems to eschew. For example, in "The Great Wall of China," he speaks of day labourers, who only look forward to their wages, and then of a sort of low-ranking supervisor. These men are seen as vastly superior and more necessary to the building of the wall, despite the fact that they are plagued by questions and uncertainties about both the Wall and the Empire itself.
At the end of "A Hunger Artist," the panther is still locked in a cage, where some of his instincts are curtailed (for instance, the instincts of running and hunting). This does not strike the reader as liberating. But the hunger artist himself is gone from the cage, and although we do not know where, the fact that the cage has been vacated is enough to make us think that some sort of liberation has been achieved. Although it is not an ideal ending, it at least gives us a picture where the hunger artist has truly been metamorphosized, into an unknown form perhaps, but one that has existence outside the bars of the cage.
Perhaps an ideal ending would have been the hunger artist finally finding the real food, after recovering his desire to search for it. This would occur after his re-cognition of his pride and would result in his re-integration into society, evidenced by him walking out of the cage.