I wholeheartedly agree that what we don’t know will forever dwarf what we think we do know. But perhaps some perspective is in order:
The universe was found to be roughly a trillion times larger and smaller than what the Ancient Greeks could conceivably measure. Over time it continues to be the case that we find smaller and larger phenomena in a hierarchical arrangement. Yet, rather than presuming an ongoing hierarchy of both larger and smaller physical structures, men (sic) universally try to terminate that hierarchy with some cosmology or quantum presumption.
Looking at the question from a Bayesian perspective the above observations suggest that the Universe is much more likely to be infinite than finite. At the very least the universe should be informally considered a trillion times larger (and smaller) than what we can currently detect of it and hierarchical in nature. That is, the Big Bang is not the universe. It’s a particle. (my pet peeve)
Deal is, every time we make a cosmology, we make it so that the whole universe conforms to one model with no part being left out. Right now, that is done via the Cosmological Principle (everything everywhere is the same at the level of galaxy clusters). There are already some cracks growing in that concept and I can pretty much guarantee that sooner or later a sophisticated enough instrument will show a (probably spherical) gradation from one side of the sky to the other in the cosmic background radiation.
I’ve have devised two rules of the material universe which I think place human understanding in the proper perspective with regard to the scope of the universe. 1) The Finite Rule: All physical phenomena are finite in extent. And 2) the Plurality Principle: All physical phenomenon are multiply manifest. Every physical phenomenon ever discovered was found to be only so big, and there could be found other examples of that phenomenon scattered all over the place.
These two rules are true for every physical phenomenon on the books, with the exception of the Big Bang because we can’t detect it’s full extent. We did the same thing with the Earth, the Solar system, the Milky Way, and now the Big Bang. Take this to the bank: the Big Bang is ultimately finite and the universe is full of ‘em.
The universe is hierarchical. Not only will there be smaller and larger phenomenon discovered, there will be more forces discovered to shape those phenomena… if we survive our own intelligence long enough to discover them. (Ask me what I think the Big Bang is.)