Here is a sketch of the future, without any specific dates assigned to its milestones. The molecular biochemistry of living beings is fully mapped and understood. The human mind is reverse engineered. It is run in software. A million variants and improvements are constructed. Molecular nanotechnology is established and becomes a mature industry, available to everyone. Anything and everything can be built efficiently and at next to zero cost given the raw materials and a specification. All disease is abolished, and aging is defeated: these are problems that boil down to control over molecules, just another form of maintaining a machine to remove wear. The future stretches out indefinitely for all living entities, whether biological or otherwise. Given that, is perhaps never too early for at least a little long-term thinking, even though we're still here in the present, working away at the very first rung of this tall ladder to the future.
From an economic perspective those who thrive in the era of molecular manufacturing and comprehension of mind are those who make the most efficient use of the matter that they own, and those who gain control over the most matter: quality versus quantity shift back and forth in the degree of advantage as the ability to accurately and rapidly manipulate large masses of matter at the atomic level and lower grows. Matter is most economically efficient when incorporated as the workings of an intelligent entity. The end state here is a continuum of thinking matter, and there are countless arrangements by which matter might be made aware. Our evolved biology is among the least intricate and least capable of these possibilities. At the most efficient we might envisage space- and matter-efficient computational processors plus the necessary workings for support: communication, energy, repair, and so forth. The higher the fraction of that mix that can be devoted to data processing and transfer, the more economically effective the entities who use that system as a substrate.
Evolved intelligences are not rational actors in search of growth above all other goals. We have parks and entertainment industries, for example. There is no reason why constructed or augmented intelligences should be any different, but equally they have one important quality: they can change themselves and their progeny in defined ways to achieve defined outcomes in mental state. The alterations and experiments that provide economic advantages will prosper. Entities who choose to incorporate an urge to growth will become the majority. At some point the value of an asteroid, a moon, a planetary crust, or a star in its natural state falls below the value of the same matter dismantled and used as raw materials for computational processing. After that it is just a matter of time before this solar system, a wilderness at present, and a collection of parks in ages ahead, is transitioned into a more efficient arrangement of matter in which near every portion of the whole is intelligent. This change will propagate outward to other stellar systems, without end, driven by simple economic considerations. A sea of cultures of a complexity and scope beyond our imaginings, and our world today the tiniest mote of a seed, that could be emulated by the smallest discrete material unit of computational processing in that future substrate.
So it is less a matter of manifest destiny that we will convert our entire future light cone into intelligence, and more a matter of economic inevitability, the destination at the end of the random walk of choice simply because some classes of choice will be made more frequently than others. The outcome of human action writ large, for a very expansive definition of the word human. All of this, however, indicates that there is something very important that we at present do not understand about the nature of reality. Nothing in our present situation as a species appears to be exceptional: stars are everywhere in vast numbers, planets also, and complex organic molecules are seen wherever we have the ability to observe them. Thus intelligence should arise elsewhere. The age of the universe is very long in comparison to the time taken for our spontaneous generation, yet we see no evidence that any other intelligence has come before us. This is often expressed as the Fermi Paradox, but is perhaps best thought of as the Wilderness Paradox, which is to ask why everything we observe, out to the very limits of the visible universe, is apparently natural and unaltered. Where are the signs of what we know is possible and inevitable for an intelligent evolved species, the conversion of matter to more efficient forms on a vast scale?
The only self-consistent solution to the Fermi Paradox that does not require some new and presently missing piece of scientific understanding is the Simulation Argument: that we are in a box and walled off from the real world, whatever that might be, created by some demiurge for purposes guessable but ultimately unknowable through any action on our part. Prosaically that demiurge might be a descendant of a past humanity similar to ours, an entity that is running one of countless ancestor simulations for scientific reasons. Far less prosaic options are also possible, in which the demiurge is simulating from first principles a radically different cosmology from its own and thus its nature and motivations are inscrutable. These possibilities of the Simulation Argument are dissatisfying to explore, however, for all the same reasons as the brain in a jar thought experiment is a dead end. Best to assume it is not true, as it if is there is nothing useful you can do about it, individually or collectively. It is Pascal's Wager turned inside-out.
It is more interesting to speculate on what it is that we don't understand at present about the nature of reality. There are numerous candidates, and most present thinking is directed towards those related to enforcing our rarity, often expressed as the Great Filter, one or more enormously unlikely steps that lie between the origin of a barren world scattered with a few organic compounds and the destination of an intelligent species engaged in repurposing of raw materials on a vast scale. All proposed Great Filters are very speculative; there is a great deal of room to argue about odds when you only have one example to work with, or events of the distant past must be reconstructed from theory, or future development of the species considered in detail rather than at a very high level, all which makes coming to any sort of rigorous conclusion next to impossible. All that is practical to achieve is to build the shape of the argument that would be sufficient if the actual numbers and proposed events in fact exist in reality. Given this uncertainty, any proposed Great Filter becomes an ever less satisfying answer the further we look outward and the more galaxies we see without any sign of massive engineering. It only serves to argue for our uniqueness, which is implausible given what we presently know and the isotropic nature of all other observed aspects of the natural universe across vast spans of distance and time.
Per our present understanding of physics and intelligent economic activity, we will turn every part of that great span, stars and all, into our descendants if not diverted or stopped by some outside influence. The cosmological noocene, an ocean of intelligence of breathtaking scope and grandeur. That the natural universe remains as it is to be used by us indicates that something is awry, however, that some vital and important understanding is missing. We as a species are still in the act of making the first fumbling explorations of the bounds of the possible with regards to what it is that we don't know.