Where are we going to be, a century from now?
Let's go back and chew on this old bone again--from a different angle.
Let me first eliminate from discussion a bunch of possible outcomes I'm not interested in examining. Total human extinction could happen in a variety of ways, ranging from wars over access to scarce resources (idiotic, but it's something humans have prior form for), to plagues, to the collapse of agricultural viability on a global scale due to climate change, sudden catastrophic collapse of unrecognized critical infrastrcture (e.g. the single factory in Bangladesh that makes the cheap quantum computer chips everyone uses to get around the central planning problem is taken out by a Cat-6 Typhoon: this causes a cascading loss of efficiency in global supply chains, leading to ...) to an asteroid mining operation gone horribly wrong. But scenarios in which everyone is dead are not currently interesting to me, as a fiction writer.
Let's also ignore transport technology, Mars colonization, climate change, the shift to non-carbon energy sources and distribution, how the hell the west will survive the shift to robotic labour (I'm assuming that by 2117 we'll have robots that can make a good stab at changing the bed linen, which is just about the acme of low-paid but algorithmically intractable jobs right now). I mean, if we're currently hearing billionaires discussing the merits of a universal basic income system, I think that tells us where the SS Titans of Capitalism is trying to steer to avoid the iceberg ...
What new fun things can I project that are both plausible, likely, and didn't feature in my earlier prognostication set a century out?
Everyone's currently focussed on anthropogenic climate change and the in-progress mass extinction. Despite the odd attempt at resurrecting extinct charismatic megafauna, the folks focussing on de-extinction of mammoths aren't talking about raising the ghosts of mammoth lice and mammoth tapeworms; only bits of the gone-away biosphere are up for revival, like preserving the frontage of a 19th century building embedded in a modern glass-and-steel office cube. Similarly, there's another extinction event going on quietly in the background: languages are vanishing, and to the extent that we can only reason about things we have words for, this may be a subtle but far-reaching loss. In fact, language is just one aspect of human culture, and what's going on in the background is a mass extinction event of variant human cultures,and their replacement by a handful of global mega-cultures. From here in the west it's easy to point the finger at Arab/Sunni islam as a rival (perceived as hostile) culture; but there's a state-supported marketing push behind it, and it's not the only one: fish don't notice the water they swim in, and our own culture is also aggressively expansionist. (Note: justifying the western free market/capitalist hegemonic system on the grounds that it brings prosperity is all very well, but it only brings prosperity to the survivors: and since 2007 it has increasing brought prosperity to an ever-smaller elite at the very apex while conditions stagnate or decline for everyone else.)
So here's a projection: by 2117, there's going to be a marked decline in the diversity of ideological and social systems in which we live, brought about by faster communications and the forced spread of the most aggressive societies. The apex societies will be mixed at ground level--there will be plenty of places where followers of religion A rub shoulders with members of economic system B--but they're still hegemonic ideologies, and there will be friction where they rub up against each other. There's also going to be a decline in the number of languages spoken: the main world languages will be down to English, Mandarin, Spanish, and some dialect of Arabic (Arabic is highly fragmented), plus surviving secondary languages with large bodies of adherents (over a hundred million each: for example German, Russian, Japanese).
We're also going to see the widespread deployment of deep learning driven machine translation and, most importantly, near-real-time interpretation. There'll be less reason for a native speaker of an apex language to learn other tongues simply because such a language gives direct access to over a billion other people and translation between apex languages will be at least as accurate as translation between English and Donald Trump speeches at this time.
And the apex languages will have changed considerably.
This goes beyond picking up new vocabulary (imagine a time traveller from 1917 trying to follow a discussion about viewing youtube videos of cruise missile strikes on ISIS positions in Syria on iPhones: the grammatical structure is accessible but a lot of the noun parts cannot be clarified without a dizzying deep dive into unimagined-in-1917 new technologies). Let's consider English--which I expect will still be around as a trade language, at least, simply because it's already so widespread. We're already seeing a shift towards simplified spelling (as practied in the US dialect) and towards abandonment of some punctuation forms; the semi-colon may be on the way out, as is the plural apostrophe, just as a number of characters used in old English (the thorn or "y"-like character, for example) vanished. More controversially English: is going to acquire a new writing system. Not all languages use a single alphabet; consider Japanese, with its eclectic mixture of syllabaries (hiragana and katakana), logographic ideograms (kanji), and romanji (roman alphabet, mostly used for loan words), not to mention arabic numerals. English currently has about three main writing systems (if we exclude shorthand notations, now a dying form, and Braile): we have roman block lettering in upper and lower case, we have arabic numerals, and we have cursive handwritten forms (also now slowly dying out). But a fourth English form is rapidly emerging in the shape of emoji, which I think are best viewed as a secondary ideographic written form optimised for visually dense text on display devices. Emoji are pared down and lack a bunch of the characteristics we associate with English grammar such as tenses and punctuation and verb conjugation ... but that's not what they're for. I suspect that over the next century (assuming we don't lose our technological infrastructure) current mechanisms for writing will be supplanted by newer ones--e.g. the replacement of discrete mechanical keys on keyboards with multitouch keyboards and then with gestural/swipe interfaces, where each dictionary word is replaced by a directional ideogram swiped across a QWERTY keymap, until eventually the ideogram replaces the alphabetic word or is auto-replaced by a corresponding emoji.
So: gradual obsolescence of some grammatical forms, appearance of entire new writing systems, unforseen changes due to the vagaries of machine translation, assimilation of loan words from other cultures, and the 2117 equivalent of "don't drone me, bro" (new shorthand to describe stuff that has become the new normal).
What am I overlooking?