Naturally I mean the WAP, which states that we observe a huge number of unbroken
causal chains which must allow the observer him/herself/itself to exist. This includes
some of the more basic building blocks of our biochemistry as well as events which
have permitted the Earth to survive long enough to allow us to evolve. Eliminate any
one of these necessary conditions and nobody* is here to make the observations!
[*I’ll broaden the “nobody” term to cover actual or possible or potential forms of
intelligent life other than us, such as cetaceans, other apes, and smart dinosaurs.
Note that the possible causal chain leading to intelligent dinos broke c. 65 MYA]
My concern is with the more recent and causal conditions, not so much the basic
building blocks established at (or before) the Big Bang. For our current civilization to
exist with conscious intelligent observers, just from c. 100,000 B.C. a whole bunch
of things had to go right (and IIRC there was mention of a bottleneck around 70,000
years ago when the entire human race almost went extinct): no major impact events,
no nearby supernovas, no worldwide famines or other catastrophic events of any
sort. Just one thing going wrong instead (as in our timeline) of going right, no human
is here today making these observations.
This is where the Inverse of the WAP, shifted into future tense, comes into play:
instead of “conditions that are observed in the universe must allow the observer
to exist”, I rephrase it to say, “These conditions are not necessarily going to hold
forever, and may very well fail to hold starting tomorrow.” That is, our luck* is
going to run out sooner or later, and likely sooner rather than later.
By way of analogy consider your own self: an unbroken chain of matings is
responsible for you being here and staring at your screen: eliminate any one of
your ancestors, and you don’t exist. Now look at that in future tense: even if
that chain of matings held up for millions of years, thus allowing your existence,
that is absolutely NO guarantee that that chain of matings will continue indefinitely
into the future, guaranteeing that you will always have descendants. You may
very well decide to have no children (I myself fall into that group), at which point
your own personal line of descent will grind to a halt, after millions of matings
throughout the ages. Perhaps you died before having a chance to procreate.
Maybe you do have kids-but none of them will ever have kids. Thus the chain,
looking forward, is likely to break due to whole bunch of factors, factors your
ancestors somehow avoided, but you or your descendants may not avoid.
Same thing for the human race and by extension Earth as a whole.
So does that mean we should be worried-very very worried? I actually would like
someone to poke holes in my hypothesis, because it does worry me, so feel free.
*[The presence of “blind luck” therefore presupposes teleology. I tend to want to
believe in teleology, for various philosophical and even mystical reasons (leaving
it at that) but I under that teleology has fallen on hard times anymore. If you
want to bring it into the discussion go ahead. 
]