Theories Of Everything: what's all that about then?

I downloaded Einstein's Relativity: The Special and General Theory as an eBook from Project Gutenberg. Written in 1916, Einstein's intention was to give the non-physicist what he called "an exact insight" into the theories. Using very precise language, with as little mathematics as possible, he shows how the theories arise, seemingly inevitably, from the consideration of experiments conducted purely in the imagination. The results of previous real experiments (e.g. those that determined the constancy of the speed of light) are used, but the theories are developed from imagined people and clocks, on imaginary trains and stations.

Einstein spent his later years in an ultimately unsuccessful attempt to derive a 'Grand Unified Theory' that reconciled his theory of gravity with the emerging theories of Quantum Physics. These two key ideas of modern physics both appear to be 'right' (in the sense of making correct and very accurate predictions about the behaviour of things) but do not sit easily together in situations where they are both required (e.g. at the 'big bang', or in black holes).

So here's another thought experiment. Imagine that, somewhere, a writer is putting the finishing touches to a new book. When the book is published, to universal acclaim, Stephen Hawking says: "This is the end of science. There are no more unanswered questions." The book is translated into every world language (except Xam - see earlier post What's in a name?). The book provides answers to such questions as: Why is there something rather than nothing? How does that something work? What is consciousness? Quantum Theory and General Relativity are reconciled; the constants of cosmology and the masses of the elementary particles emerge naturally from the new theory. The distribution of the primes is no longer a mystery. The author is awarded Nobel Prizes in physics, chemistry, medicine, literature and for peace, as well as the Fields Medal for mathematics.

Unless there's an inherent limit to what human thought might achieve, this is surely a possible scenario. I'm wondering what such a book would be like. Would it be the work of a physicist, or a philosopher, or maybe a religious scholar or a mathematician? Would it conform to Einstein's belief that "Most of the fundamental ideas of science are essentially simple, and may, as a rule, be expressed in a language comprehensible to everyone", or would it be filled with such complex maths that a lay person would have to take it on trust that the book was as important as the handful of people who understood it said it was?

Which section of the bookshop would it be found in? Would it be a Richard & Judy Book Club recommendation?