Is Buddhism life denying or life negative? My question tag is similar to this one but I am asking a different question.
I am reading DN15 the mahanidana sutta where the Buddha says;

Suppose there were totally and utterly no rebirth for anyone anywhere.
That is, there were no rebirth of sentient beings into their various
realms—of gods, fairies, spirits, creatures, humans, quadrupeds,
birds, or reptiles, each into their own realm. When there’s no rebirth
at all, with the cessation of rebirth, would old age and death still
be found?


&quot;No, sir.” “That’s why this is the cause, source, origin, and
condition of old age and death, namely rebirth. ‘Continued existence
is a condition for rebirth’—that’s what I said. And this is a way to
understand how this is so. Suppose there were totally and utterly no
continued existence for anyone anywhere. That is, continued existence
in the sensual realm, the realm of luminous form, or the formless
realm. When there’s no continued existence at all, with the cessation
of continued existence, would rebirth still be found?” “No, sir.”

Suppose in a hypothetical scenario in which all sentient beings which the Buddha mentions attain Nirvana and there is no rebirth here on planet Earth, wouldn't life as we know it vanish (Except for the trees)?
If there is no life, there is no Dhamma and no Buddhism. In that case wouldn't lifeforms emerge and evolve all over again on Earth or on some other habitable planet as they came to being in present form and all cycle of samsara and suffering and birth of Buddha all over again leading to absurdity of the whole endevour?
In that case wouldnt Buddhism be an effort to finish the sentient life and act against lifeforce as it is an effort to finish rebirth?
Why your question and all the other similar questions you linked are not getting a direct answer, but a shuffle is because the Buddha did not give an answer for such questions.
You may read many shuffles here, but the truth is questions such as Begining of life, end of life (i.e. beginner and end of Samsara); or hypothetical scenario in which all sentient beings attain Nirvana will receive a cold silence as an answer from the Buddha.