Nature has already dealt with five mass extinctions and the human species now seems determined to cook itself out of existence. But the earth will continue to exist and ultimately will heal itself once again ... without us. Nature has forever, we don't.

...this "Life" thing is very rare, in fact, the earth seems to be the only example of it in the universe (that we have been able to find).

All of our planetary biological "life" is interconnected and interdependent, what Earth's "Life" is, is actually one huge ecosystem made up of millions of separate, but definitely interdependent, species.

It isn't a far stretch to imagine the entire system collapsing from some major shock to the system (like extreme climate chaos) after having developed over so, so, long into such an intricate and delicate balance of interdependent parts.

Complex systems are much more vulnerable to complete break down than simple systems, and our biologically living earth wide system is incredibly complex.

so that naturally begs the followup question: since "life" rebounded after each of the five previous mass extinctions, why would another one completely obliterate "life" altogether? What would be different this time? The extinction of the human species and many other life forms currently in existence would not necessarily entail the extinction of "the essence of life" altogether. Or I am misunderstanding the hypothetical scenario as presented?

...the previous extinction event massive, they simply weren't severe enough to halt the overall system.

Those previous extinctions just never reached a threshold that once passed, life could no longer regenerate.

But when you think about it, of course there must be a line, or tipping point, after which all life on the planet ceases.

For instance, what if our thin atmospheric layer suddenly blew away from the force of a massive solar flare (or something, I have no idea what it would take, but I do believe that earth as a dead planet is possible. There's no reason to believe that 'life' is guaranteed here).

defining "dead planet" as a scenario where "life" as we define "life" is no longer present in any shape, form or fashion whatsoever, then although I can't see that as being in the realm of probability due to historical precedent, nevertheless, granted it can't be completely ruled out as a scenario in the realm of possibility. But not being an environmental scientist, I can't imagine what a horrific and cataclysmic event would be required to cause that to occur. Just saying....

But chances for us? Questionable. We're taking a lot with us if we go, but other life will continue. IF we have the smarts to make a u-turn.

and I agree that life and the earth will continue. I stand by my original post #1 above.
"For all things are formed by nature to change and be turned and to perish, in order that other things in continuous succession may exist." --- Marcus Aurelius