What language will people be speaking 5000 years from now? That is a silly question and my linguist friends will no doubt get upset. They want to study languages in their native state and luxuriate in the various ways humans have found to communicate ideas. They are chagrined because human languages are being lost at an alarming rate and they are making efforts to record the vestiges of the thousands of languages which were once in common use in isolated areas. It is a losing battle because for most people it is more economically valuable for them to speak one of the major languages. And even most major languages are congealing into a limited few mostly moving toward English.
Mandarin Chinese has the almost a 1000 million native speakers with Spanish second with 329 and English third with 328 but English has the most people chosing to learn it as a second language. Over a vast period of 5000 years of time postulated none of these languages might still be intelligible to anyone as a first language. And yet, languages which have been written down have still been recognizable and useable a thousand years later, Latin for example. With popular media such as recorded TV a popular language with an abundance of interesting content might last even longer. A top quality HDTV now delivers a satisfactory story telling medium and that seems to be what people want most, at least for now. Even more interactive media can be transmitted directly to these audio / video devices and it doesn’t seem that improving the quality of the media ten times over would do much to improve the human experience. So the mediums of screens and internet and improved input devices would not change the language used but would instead tend to stabilize it over the whole world.
What would be improved might be linking together of people to those other people with whom they would most enjoy communicating in a more instantaneous interactive way. This of course is what is being implemented more fully as I write. It is unknowable how far that will go but my question is, will it change the language. New words will come and go but as a general rule writing that uses many newly popular words dates itself and is soon thought of as out of fashion and old. The basic language, which is the simplest and the most commonly used is what persists the longest. With a whole world of people speaking the same language there would be great inertia to any changes to the basic language. At the moment English has the greatest assemblage of readily accessible human knowledge because spoken Chinese is not intelligible to all its people and even its written language has several related but not totally interchangeable forms, which may be seen on the Chinese Wikipedia. China is definitely on the rise but even there they are moving toward an English style for their writing and speaking. Americans and the rest on the non-chinese world are not moving toward learning the Chinese language. What access there is to that vast culture is mostly through translation.
Language tends to follow those who the controlling political power and for the last couple of hundred years that has been English-speaking peoples. Language also follows the money, like much else, and that has also been largely controlled by English-speaking peoples. If the current trend of the Chinese people choosing to learn English then even if they do control the military and monetary power the language of the future may still remain English.
When everyone is watching the same TV and other media there is a smoothing out of basic inconsistencies even though local dialects create new ones. But the local ones are transient in this context like popular specialized words. That will tend to make the universal English drift toward a tighter basic language but with a greater number of new words for describing local events and things. These words function more like personal identifying names do for individual people and are not part of the basic language.
Some simplified universal language like Esperanto might become popular but English has so much inertia that it will be difficult to displace until there is a mass of good literature and TV and other media. Some simplifications of the words in the English might be introduced such as the Probaway Numbers system which are more easily spoken numbers with unique single syllable sounds which are easier to use and to remember. This system was created because if anything is easier to use it becomes more useful. It simply replaces difficult to pronounce number-words with similar single syllable number-words.
There will probably arise many other simplifications of the standard spoken English. These undiscoved things may be similar to: the decimal notation system, or the Metric measurement system, or even the alphabet system of notation system, which are easier to use and eventually permeate the whole society. With a one world society, which we now have because of the internet, there are forces of convergence moving society towards the easiest and best way to do things — even speaking. Shakespeare’s local London-English is still easily understood after 400 years with only the written word to stabilize the language. Now, with a vast amount of knowledge in English, to stabilize it, there is much more inercia to drag us ten times longer into the future.
Current spoken English will be recognizable in 5000 years.