What does Buddhadasa say about rebirth after the break-up of the body? i came across the teachings of Buddhadasa, he seemed to preach that rebirth is just a state of mind cycled throughout the days; greed, lust, peace, etc.  That makes sense. But did he talk about what happen after break up of body or conventional death?  Am i missing something?  so if that is true, then eventually everyone will reach Nirvana at the end if we wait long enough (because according to him, there cant be cycles of state of mind if there is no rebirth)? Did he present new idea of   of rebirth or I still have a lot more to read from Buddhadasa?  I can't seem to find his ideas of literal rebirth.   Thanks.
Buddhadasa taught "literal rebirth" is something mental, in the here-&amp;-now. Since the Pali word "jati" ("birth") literally refers to something mental, why would the superstitious speculative idea occur that an imaginary "physical rebirth" is "literal"? 

The word 'birth' ('jati') refers to the production of 'beings' (per SN 12.2). Suttas such as SN 23.2, SN 5.10 &amp; MN 98 say 'beings' ('satta') are merely 'views' &amp; 'verbal designations' born of 'strong clinging'. Therefore, 'jati' or 'birth' is something 'mental', in both original Buddhism and in modern Hindu India. 

As for he answers to your questions, they can be found in the book by Buddhadasa called Two Kinds of Language. 


  Now, going a little higher, we come to the word "birth" (jati). In
  everyday language, the word "birth" refers to physically coming into
  the world from the mother's womb. A person is the born physically only
  once. Having been born, one lives in the world until one dies and
  enters the coffin. Physical birth  happens to each of us only
  once. This birth from the mother's womb is what is meant by "birth"
  in everyday language.
  
  
  
  Now let's consider the word "death". Death in everyday language means
  that event which necessitates putting something in a coffin and
  cremating or burying it. But in Dhamma language, the word "death"
  refers to the [traumatic; sorrowful; suffering] cessation of the idea mentioned just a moment ago, the
  idea of "I" or "me". The [traumatic; sorrowful; suffering] ceasing of this idea is what is meant by
  "death'' in Dhamma language.


About the later-day corruption of 'jati' into something 'physical', Buddhadasa said: 


  People language is used by the ordinary people who don't
  understand Dhamma very well and by those worldly people who are so
  dense that they are blind to everything but material things.


Such worldly people are so dense &amp; blind they label as 'materialists' those who don't subscribe to superstitions of 'physical rebirth', which is illogical &amp; contradictory, given it is they, who believe in 'material physical rebirth', who are obviously 'materialists'. 

In summary: 


'Literal rebirth' is something 'mental'. 
Believers in 'physical rebirth' are logically 'materialists'. 
Buddhadasa appeared to say there is only one life. 


As for the term 'kaya', found in the translated sutta phrase: 'break-up of the body', it does not necessarily mean 'physical body'. 'Kaya' literally means 'group' or 'collection'. MN 44, for example, says the 'sak-kaya' is the five aggregates. Since the quality of the five aggregates are changing from moment to moment, particularly in the common worldly 'person', obviously the phrase 'break-up of the kaya' may not refer to the termination of life. 

For example, as soon as I log off Buddhism Stack Exchange, obviously the aggregates answering this question (such as the sankhara aggregate thinking with the thought content of this question; and the visual consciousness of the sense object Buddhism Stack Exchange) will end.