The history of the genus homo is complex and still incompletely known, and while it’s always tempting to draw lines connecting the data-points we currently have it’s also potentially erroneous. Moreover there seems to be genetic evidence that our own branch of homo passed through a “bottleneck” around 70,000 years ago (possibly coinciding with the Toba supervolcano event) that seems to have resulted not only in an explosion of language thereafter but also, pace Yuval Noah Harari, in the human brain becoming more fantasy-oriented (hence the invention of gods and goblins, ghouls and ghosts). As we learned to speak we conceptualized and abstracted, and as we conceptualized and abstracted we demanded more of speech.
With regards to the future of language, if we somehow avoid exterminating ourselves within the next 200 years and if some semblance of today’s global inter-connectedness persists, it seems likely that we’ll arrive at a handful of dominant languages based on economic realities. English will probably be among this small group; most people today would likewise mark Mandarin as a candidate. Whatever happens, there will still be significant local variations that will drive differentiation into dialects that ultimately become mutually incomprehensible. For example, US English is the RISC version, having only three tenses, no adverbs, and around 1,500 common words. This results in massive use of phrasal verbs to compensate, as well as grammatical quirks such as “I didn’t do it yet.”
Meanwhile in India, the phrase “you are too clever” isn’t an admonition, it’s the local version of “you are very clever.” And back in the UK the range of regional dialects is so great and so deep that a working-class person in Newcastle will have exceeding difficulty in understanding a working-class person from Cornwall.
As always, language is torn between the need for comprehensible communication across groups and the need for groups to distinguish themselves by means of altering language so as to use it as a group identity signal. That isn’t going to change. The future of language will be one of continued tension between these two human needs, and language(s) will continue to evolve accordingly.