Personally, based on absolutely nothing concrete, I suspect that the big bang theory is nearing its end. Once technology reaches a new plateau I expect that the idea that the universe is limited as to time and space with be disproved.
Indeed, I expect that it will be found that the universe is not finite. In other words I think there is and endless string of universes that, like the stars, are constantly dying and being born.
This might be the reason why a universal theory of everything has yet to be formulated.