Understanding the beginning does not mean we would know the end. In the book the Five Ages of the Universe, the authors state a case for a universe which lives on for trillions of years, so long that even the fundamental particles completely decay.
Dark matter has been mapped:
BBC NEWS | Science/Nature | Hubble makes 3D dark matter map
But I do agree - these are mysteries we need to study and find good answers to. We may not really know the right questions yet.
