In this scenario, my life will begin.
But more seriously, it depends on what kind of zombies we're talking about and what the definition of a zombie is.
Typical decaying, stupid and slow zombies? A small problem that can be easily solved, because these zombies in a realistic scenario are not a threat to "intelligent" animals like us.
Of course, something like that won't happen, because we don't live in a fantasy world.
Zombies can exist in a sense, but it doesn't look like, for example, in The Walking Dead.
Even in the natural world, there are "zombies".
We also don't have to look far, because some people meet some of the conditions for being a "zombie".
In general, the global SHTF crisis is my CTB date.
Maybe I'll watch everything burn for a short while, but when the problems start attacking me in a very unpleasant and direct way, that's when I commit suicide.
I don't want to participate in a hopeless fight.