Nirvana is not really a place but is a state of mind whereas there's no attachments, no anger, no craving, etc.; but there is full peace of mind. Since there are different rafts within Buddhism, and since it is very allowable to question and challenge even the most basic teachings, there's no monolithic thoughts on the subject, and many question what it may be about or even if such a state exists.



There is no unchanging soul ("atman") in Buddhism, and one does not "reincarnate" (with the exception of the lamas in Tibetan Buddhism), but the word "rebirth" normally is used. It is not the "soul" that is reborn, but a stream of consciousness instead that flows from one rebirth to another. It is believed that many may be able to tap into that stream and know some things about their previous rebirth(s) through deep meditation.

However, to repeat, there are many Buddhists who question much of this.



Rebirth may continue unless one reaches a state of nirvana, but you ask a very good question in regards to what would happen if all human and all sentient life were to die off. I have about three dozen books on Buddhism, and I don't recall that question being covered, so I simply don't know the answer. However, I'll see what I can find from another source.

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"The further the spiritual evolution of mankind advances, the more certain it seems to me that the path to genuine religiosity does not lie through the fear of life, and the fear of death, and blind faith, but through striving after rational knowledge."-- Einstein

I just talked with a Buddhist scholar that I deal with when I get into questions that I can't cope with and he says that there is no "Buddhist answer" to the question posed in regards to what would happen if all came to an end, what would happen to those sentient beings involved in the rebirth process. There's apparently no mention of such in the Pali Canon or any of the sutras.

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"The further the spiritual evolution of mankind advances, the more certain it seems to me that the path to genuine religiosity does not lie through the fear of life, and the fear of death, and blind faith, but through striving after rational knowledge."-- Einstein