Thinking long

Sometimes I try to imagine what the world will be like in 2100. That seems endlessly far away, but it's worth considering there are probably already a billion people alive today who will still be alive then. In particular, I consider the following to be pre-determined elements

1. There is going to be massive though at present radically unknown levels of global warming. The first order impacts (extreme heat, loss of watersheds from glacial melt, and sea level rise with attendant greater damage to coastal cities from storms) are going to range from very serious to unbelievably catastrophic if we both fail to seriously abate GHG emissions and some of the more alarming feedback loops go into effect.
2. There will be a great deal of population growth between now and the middle of the century, almost all of it in the cities of the global south; combined with climate change, this makes mass migration and population displacement of a scale unseen since the 16th century a virtual certainty.
3. Human bio-engineering in multiple registers is coming.

Of course, at that time scale, the uncertainties are far more numerous:

1. How will religion evolve? Will there be anything akin to the global Fourth Great Awakening among Christians which began in the 1970s, or the major growth of political Islam since the 1980s? Or, conversely, will the long secular trend toward secularization resume?
2. How will the disease context change? Downside possibilities include new diseases/pandemics and the loss of effective antibiotics. Upside possibilities include major biomedical breakthroughs as a result of genomics and AI; these could both happen in parallel.
3. How will human bio-engineering be rolled out? Only for the rich? Open source free-for-all? Mandated by governments, e.g. genetic “vaccinations”?
4. In the face of climate change, how will governments (and NGOs?!) address the imperative to pro-active geo-engineering, of what sort with what consequences (both intentional and unintentional)
5. Will the Fourth Industrial revolution (AI+biotech+robotics+nanotech+new energy) create new jobs and industries faster than it destroys old ones? How will the spoils from the productivity gains be shared? How will the "transitional losers" be treated, and what sorts of political backlash may ensue? 
6. What will be the global demographic trajectory of the second half of the 21st century? This is both in terms of total population, but more serious will be the question of where all these people are going to go (e.g. the destination for the inevitable migrations).
7. How will identities transform? Questions of local, national, global, and “ageographic” identities (religious, cohort, professional, gender, etc) are extremely hard to foresee with any certainty at this time-scale.
8. How will military competition evolve? Will nuclear weapons or other WMD-scale weapons be deployed in anger and at scale between major powers? (This hasn’t happened since 1945, but past returns are no guarantee of future results) What sorts of new military-capable actors will emerge?
9. What sorts of new political institutions may emerge? At what geographic scales? Which existing ones will fall into irrelevance?