I sort of have the impression that writing will be around for a little while, but will ultimately prove more trouble that its worth in any quantity. Why write when the person you want to talk to with is likely very close by? And in my impression, stories are better told than read. They are dynamic that way, and I think with face-to-face contact, the old novel pales in comparison. There’s context, relevance, nuance and inflection in our voices that text has a hard time living up to. There will be no need for laws or accounting (a prime reason cuneiform was invented in the first place) and the energy/time spent learning to read and write might be better placed elsewhere.
I think the key is the static nature writing can imbue into culture. I’ve long felt that it slows cultural development by putting myth and language into some sort of stasis. Look at how the bible has done for cosmology and ethics all over the world… Something that was meant for people thousands of years ago in the middle east is now everywhere nearly intact (contextual, copying error and translation issues are a factor) because some dudes wrote it down.
My thoughts aren’t for any lack of love for writing on my part. I’ve written calligraphy for 20 years now (just got mad loot for wedding invites, woo!) I just don’t see humans needing or wanting it in a thousand years. The only exception I can see is BlueHeron’s thought for some kind of pidgin for brief inter-tribal communication between shindigs.
As for changes in the meantime, a lot of our scripts are created for 2 major purposes: speed of writing and ease of reading, both applying to bodies of text. Once people stop writing huge texts for lack of easy ink and papers and domestic animal skin parchment, I see change happening fast, probably initially in favor of concision. Lots of accents and diphthongs at first, giving way to drawing. Less abstract pictographs will probably eventually become the norm for pidgins as languages spread apart and some become nearly mutually unintelligible. At that point, writing may once again reach a practical equilibrium. Full circle.