SuttaCentral
It’s nearly 5 in Sydney. In two hours I will be giving a talk. Immediately as the talk ends, the lights go out all over the world: this is the last Dhamma talk that there will ever be. I am the only one who knows this, but I can’t tell anyone.
What do I talk about?
How about what wonderful this world is with all its Mara, Deva, Naga, Purisa. And what make life worth living even just for a few more hour and that’s it!
What makes the mind
truly satisfied?
For us to say
The last goodbye
I’d say keep it classic: gradual training ending in the Four Noble Truths, just in case anyone there is ripe for stream entry!
Bhante, tell them about the breath.
The Simile of the Mountain and spiritual urgency in general.
Edit. Nibbana
Hmm … this is a similar question to what another monastic I know recently asksed. He obviously loves surveys and asks everyone the same questions. In this case there were questions such as
If you would meet a layperson who is terminally ill and will die soon, and they just discovered Buddhism and want to understand what it means before they die, what Sutta would you recommend, and why?
I find it always difficult to answer such questions. I simply don’t believe in a “one size fits all” solution.
Just as an example, there are three different people whom I know, who are all deeply committed to the Dhamma, but who approached it from very different angles.
So people are different, very different, and whichever topic you choose for the world’s last Dhamma talk, there may be someone for whom that just hits the point! My advise would be: Just follow your heart … 
Thanks so much everyone, I was able to take your ideas and make a Dhamma talk from them!
It’ll be up at Lokanta Live soon.
It was an elegant weaving, and even managed to give a nod to grumpy old people as well. 
& nice remarks about breathing in and out mindfully.
I have a preference of the Four Noble Truth to be taught as the last Dhamma talk. However, in DN 16, the Buddha had another approach:
Then the Buddha said to the mendicants, “Perhaps even a single mendicant has doubt or uncertainty regarding the Buddha, the teaching, the Saṅgha, the path, or the practice. So ask, mendicants! Don’t regret it later, thinking: ‘We were in the Teacher’s presence and we weren’t able to ask the Buddha a question.’”
When this was said, the mendicants kept silent.
For a second time, and a third time the Buddha addressed the mendicants: “Perhaps even a single mendicant has doubt or uncertainty regarding the Buddha, the teaching, the Saṅgha, the path, or the practice. So ask, mendicants! Don’t regret it later, thinking: ‘We were in the Teacher’s presence and we weren’t able to ask the Buddha a question.’”
For a third time, the mendicants kept silent. Then the Buddha said to the mendicants,
“Mendicants, perhaps you don’t ask out of respect for the Teacher. So let a friend tell a friend.”
When this was said, the mendicants kept silent.
Then Venerable Ānanda said to the Buddha, “It’s incredible, sir, it’s amazing! I am quite confident that there’s not even a single mendicant in this Saṅgha who has doubt or uncertainty regarding the Buddha, the teaching, the Saṅgha, the path, or the practice.”
“Ānanda, you speak from faith. But the Realized One knows that there’s not even a single mendicant in this Saṅgha who has doubt or uncertainty regarding the Buddha, the teaching, the Saṅgha, the path, or the practice. Even the last of these five hundred mendicants is a stream-enterer, not liable to be reborn in the underworld, bound for awakening.”
Then the Buddha said to the mendicants: “Come now, mendicants, I say to you all: ‘Conditions fall apart. Persist with diligence.’”
These were the Realized One’s last words.
The only thing that came to mind for a last talk is along the lines of what a person can do for their parents:
“But, bhikkhus, if, when one’s parents lack faith, one encourages, settles, and establishes them in faith; if, when one’s parents are immoral, one encourages, settles, and establishes them in virtuous behavior; if, when one’s parents are miserly, one encourages, settles, and establishes them in generosity; if, when one’s parents are unwise, one encourages, settles, and establishes them in wisdom: in such a way, one has done enough for one’s parents, repaid them, and done more than enough for them.” -AN 2.33
Essentially, people have to be inspired to recollect whatever notions they already have about faith, generosity and virtuous behavior, and that they would have always been safe relying upon them, therefore revealing the potential of wisdom in the end. They have to be assured that they were right to have preferred being good, even if they only ever thought about it.
If this is the case, then, you may talk about “the world is empty”, because “the world is empty of self or of anything belonging to self”, according to SN 35.85 = SA 232:
Pages 93-94 from the-fundamental-teachings-of-early-buddhism_Choong Mun-keat 2000.pdf (138.3 KB)
It would help if you said it exactly as it is, and I say it out of experiencing a particular pull from that simple sentence, followed by natural quietness. Maybe add that I love a good koan, and this is one of those
I wish I could be there for that talk 
Anumodana Sadhu 
Talk on the Buddha’s last words…how he chose to speak about diligence/not being lazy when it comes to striving for the end of suffering. How important Right Effort is for sila, samadhi, and pañña.
Hm, a bit late…
For me one more aspect would be good to consider. When the cousin of the Buddha had a really bad day, depressed about his non-progress - - - he was called to come to a speach with the Buddha.
The finalizing of the discourse was something like “Rejoice! I’m here with you”
See here:
https://suttacentral.net/sn22.84/en/sujato
(…) Rejoice, Tissa, rejoice!
Abhirama, tissa, abhirama, tissa.
[10.15] I’m here to advise you, to support you, and to teach you.”
Ahamovādena ahamanuggahena ahamanusāsaniyā”ti.
(…)
In german this comes even more at the point
Samyutta Nikaya 22.81-90
31. Sei heiter, Tissa! Sei heiter, Tissa! Als Berater bin ich ja da, als Helfer, als Unterweiser."
I think, that it is not unfair/unwise to point the anxious people (with little time to live) to the presence of the master, of the Other, kind, compassionate human being. It makes the whole cataclysmic moment a common share - where such sharing is known to be kindling (at least) for mammals (if not for all sentient beings).
