As many had done research on what happens when Arahat of the level of “once-returner” and “non-returner” go to after their earthly existence and given their point of view based on Mahayana prospective.
In my point of view the “once-returner” must have attained enough or had enough of merits to be reborn into the higher realm of gods or choose a human existence as his next life.
The “non-returner” will cease to exist after their final earthly body as many had pointed out in this topic according the Theravada tradition.
This brings out an interesting question of where do the “Non-returner” Arahat go to after this?
I would like to relate to an extract of content of a book titled “everything arises, everything fall away” by the great master of Thai Forest Tradition: Ajahn Chah on page 134:
Gunamantani was a disciple of Venerable Shariputra who prepared to go on ascetic wandering. As his teacher, Sariputra wanted to check the extent of his disciple’s knowledge before he set out on his own; he wanted to find out is Gunamantani was genuinely prepared for it. Sariputra questioned him, ”Should there be some person, such as a sage or ordinary householder, who ask you. ‘ Venerable Gunamantari. When enlightened being pass away, where are they reborn?’ How will you answer them?”
The Venerable Gunamantari replied. “ I will say to them, ‘ Form, feeling, perception, thought, and consciousness appear and then cease to be.’”
I read this when I was in my studies, and it didn’t make any sense to me. One person was asking one thing, the other is about replying something else, and the two don’t seem to meet at all. Of course, it really make sense, they really does answer the question in the most genuine way; it’s just that I was so ignorant to understand. When Gunamantari was asked what becomes of the Ariya who pass away, he didn’t say it directly. He only answered that “ Form, feeling, perception , thought and consciousness, having appeared, then cease to be,” Because such person do not die. There are merely aggregates appearing and disappearing. They don’t dwell there. They don’t die or take birth. That’s all there is to the matter.