Willem de Sitter might have it !

 In lieu of all the details for understanding the nature of the Universe for decades and many new findings, it appears that Willem de Sitter, early 20th century Dutch physicist, may have the best over all depiction after all major models that have been submitted. (Both Einstein and de Sitter had withdrawn their static and spherical models by 1930's.)

The Universe may be closed, where upon it will contract to singularity or nothing. Einstein and de Sitter tended to favor a closed universe. It may expand like an open cosmos, as was explained with Alexander A. Friedmann, Hubble, but will become so diffuse as to be devoid or empty on the macroscale. A pressure sending bodies completely out of touch with one another. For as long as it lasts, the speed of light may not be a useful measure for gauging by then. It is widely believed that if fusion or other source of light becomes extinct then the universe would accordingly be depicted as unlit, dark

 Even now, new studies can span between the conclusive scenarios but they face a reality of an empty Universe ultimately. (Quite the same if the Universe self destructs completely 'before its time'. What is around if it becomes a singularity or nothing. What will there be? If so diffuse, what then will there be to behold or experience or detect?)

Albert Einstein, clinging to Ernst Mach, held that space and time could not exist with having matter present to measure it. Unless the supply of mass was infinite, the extent of spacetime could not be infinite, unless there is not matter.

de Sitter described a universe infinite in extent in 1916. Einstein had to drop Mach's idea from general relativity as incongruent. He had to accept that space is separate from matter.  This latter was reinforced by Alexander Friedmann' paper in 1922.

Simply, the de Sitter model operates after all on no presence (or dependence) of matter, which in now being found according to some models. It has nothing, The de Sitter Universe, it appears, operates on radius and "positive" pressure (like antigravity. curvature) and overall there seems to be nothing else for at least the largest macroscale. The de Sitter model supports the far future of the cosmos as unlit in the second age and can still expand.

Notes:

"consistent model where our universe was best described as a de Sitter universe at about a time t=ten to minus 33 seconds after the fiducial Big Bang singularity, and far into the future."

"a de Sitter universe has a Hubble Law that is not only consistent through all space, but also through all time"

"Eventually there will be almost nothing left but the vacuum energy, tiny thermal fluctuations and our universe will have become a de Sitter universe."

"All cosmological models with a non-zero cosmological constant will approach a de Sitter universe in the far future", wrote L.M. Krauss and R. Scherrer in a 2007 article.

"if our vacuum were metastable, we are not likely to exist in the late time regime."

wrote L.M. Krauss and J. Dent in 2007.

A base with spinor and S-Matrix is supplied by Adrian David and Yasha Neiman, can be found arxiv: 1906. 01058.