All we can say in the long run is that, if the future will resemble the past, life will continue to expand beyond the frontiers of this planet and in continued diversification.
Life started from a single simple organism to an innumerable variety of organisms, most of which are extinct and of which we will never know anything at all. Nevertheless we can assume that all of them have left a mark on the history of our planet that has shaped current events, for even apparently insignificant events like the flapping of the wings of a small butterfly may cause are preserved over eons by the very precise laws of cause and effect that preserve the coherence and harmony of our world. So the same should go for bacteria or viruses. Everything plays a part and every part counts.
How will life expand? Well, we are the vehicles of that expansion. Without civilizations, no group of (intelligent) animals could learn how to manipulate the vast diversity of objects required to make spaceships and all the rest. Language was needed to transport manipulative abilities from one group to the next, from one generation to the next. Culture is like a net that collects all the good ideas that solve or help to solve some outstanding problem (even if it is just "how to create a good ice-cream", "how do I put this theory into practice", "how do these different ideas relate", "how can we accept novelty in this field by maintaining what we already achieved", etc). There is an unlimited number of problems to solve, much more than appeared to the senses only. For culture deals with everything the senses had to deal with but also much more. It deals with culture itself (how ideas relate to one another), with its physical artifacts, and also with its emotional products. A culture generates highly specific cognitive and emotional states, shaped by the inputs of countless of its members, dead and alive.
So the first place where diversity will emerge once civilizational beings are into place is in their thoughts and emotions (we should notice that all animals are intelligent to some degree, and some are more intelligent than men in some respects - for instance in orientation through the magnetic pole - what distinguish us is a highly developed culture that gives rise to very complex civilizations, that is what non-talking animals lack). This will likely be reflected over time (over millions of years) in different physical outlooks for those that specialize on different aspects of this culture. Over billions of generations one specie of talking animals will almost certainly give rise to many species whose behavior is rapidly overruled by culture and whose physical powers may slowly be expanded by the application of technology. The first ones should be cybernetic individuals or highly modified genetic versions of the initial species. While genetics and cybernetic devices may at first be used just to prevent or cure severe diseases, it will (again it may take hundreds of thousands of years, or much more) be extended to less severe diseases, and then to perfect (perhaps in individuals that greatly desire it - we may fancy) certain abilities. Over time this may lead to physical differentiation, in a civilizational species, and therefore to physical diversity. However, if cybernetic and genetic mutations can indeed create beings with the ability to encompass all of the relevant culture (and this is not at all clear), then physical diversity may not prove necessary, instead, a single type of individual may encompass all the alternatives, all the techniques, all the relevant problems and solutions, he might have a memory that allows him to have instant access both to Mozart and Nirvana, to Louis Armstrong and Elis Regina, and to understand all of these things too. So, after a period of physical diversity (which may happen because only a part of the members of the species will likely want to change their nature) it may happen that uniformity of physical appearance will dominate, although hiding an incredible diverse inner world (much vaster than we are able to conceive in our present state).
This might not happen in planet earth, of course, we might explode it to pieces first. But it is seems reasonable to suppose that it is bound to happen on planets with creatures that have civilizations and if we provide for sufficient eons for their intellectual, artistic and spiritual worlds to expand. After a considerable amount of time (in the scale of millions of our years) such a civilization would easily colonize planets around and other solar systems. We know that there are places in the galaxies where stars are much closer than we can observe. In our case the closest star is at approximately 4 ?? light-years away. But in the ?? system, stars are just ?? away. It is likely that these agglomerates of large quantities of stars is the best place to find rapidly evolving space-oriented civilizations. On the other hand, when we look at the stars, we cannot find any clear signs of artifacts made by the innumerable civilizations that certainly surround us. Why is that? Well first of all we are almost completely blind when it comes to watching extra solar entities. All we can see are gigantic stars, however, this at least shows that civilizations throughout the universe were unable to build artifacts so big, shiny and different that we can actually observe them with our current telescopes (if we dedicated all the money we currently waste on weapons to kill ourselves to the design and construction of spatial telescopes, we would probably have already have found many evidences of intelligent life around us - it is certainly a case of "we see what we search for").
Diversification will probably be intensified when extraplanetary colonies develop.