A difficulty in predicting where things are going is that they often don't develop in linear ways.
It is easy enough to add up some numbers and draw a line through them and expect the same change to continue in the future. But that is only how it happens in a narrow short-term context. More importantly, there are discontinuous jumps in how things develop.
That doesn't mean that it is altogether impossible to estimate what the future will be. It just means you have to take different kinds of discontinuities into consideration. And some of them aren't necessarily all that mysterious.
For example, various forces or factors might build up towards a threshold or saturation point and then things change into a new state.
If there is a threshold change to a new state probably depends on the speed of the preceding change.
There is the old story of how to cook a frog. If you drop a frog into boiling water it probably jumps our right away. But if you put it into cold water and very slowly heat the water, the frog might not notice that it is being cooked before it is too late.
If things change quickly enough for you to notice, you will probably make a change once the change is "too much" for you. If you don't notice, you might not.
If a population is very gradually subjected to more an more oppressive government control, it might not notice. It might just assume that that is the way things are. However, if it happens in a short period of time, the population will revolt in one fashion or another.
If people notice that they are getting rapidly overloaded with information, something will be done about it. There will be a fairly sudden change in state when enough people reach a certain threshold point.
If nothing much changes in one's life, one might not even get the idea that there is a point in working on one's personal growth or expanding one's consciousness. But if lots of stuff is happening in one's life that one doesn't quite know what to do with, one will naturally be on a search for increased understandings and abilities. Just extending the trend of "more and more stuff going on" is worthless. There will naturally be jumps in ability and consciousness as one masters different parts of one's life.
If a certain type of problem is increasing noticably in volume or frequency, that means that solutions will be developed. More violence or ecological destruction doesn't just mean that we will have even more violence and ecological destruction in the future. It means that something will change about it.
Looking beyond the threshold points can be a much more empowering experience than simply extending trends a little bit.
The short-term increase in a negative trend will, if noticed, usually be followed be a positive trend that solves it or voids it.
Another type of development that might not be apparent in the short term is the integration of polarities. If a polarization into different factions is noticed, it will normally be followed by some kind of integration into a new situation. Thesis vs antithesis becomes a new synthesis, as Hegel described it.
So, if you see increased polarization, that doesn't just mean that we will see more polarization in the future. Rather it means that sooner or later the polarized factions will come together in some kind of synthesis that isn't immediately apparent from studying any of the polarities separately, but that possibly might be predicted from studying them together as a system. Very often none of the sides will "win", but a new situation comes out of their interplay and ultimate integration.
Another way of looking at discontinuous jumps is in terms of paradigms. If an existing paradigm is increasingly failing to solve the problems it needs to solve, that means that a new paradigm is coming up soon. That will be a discontinuous jump. The new paradigm, by its very nature, can't be directly deducted from the old paradigm. It will be new. However, you can predict that there will be a shift soon by looking at the inability of the current paradigms to solve the current problems.
The political system in many areas of the world is failing to deal with what they are expected to deal with. So, new paradigms are around the corner. That democrats or republicans fail to solve society's problems doesn't meant that that's what we will have in the future. Much rather, that means that thats particularly what we WON'T have in the future, because it doesn't work.
Old paradigms will tend to resist the new paradigms that will override them. And the new paradigms will not "make sense" if one tries to explain them wearing the glasses of the old paradigms.
The trick is to cultivate the new paradigms while they are still just wild ideas. And to look beyond the shifts that will happen towards the new states that will replace the old one's.
Much prediction and trend study is simply attempts to perpetuate and defend the old paradigms. I'd say that any prediction that merely predicts more of the same is suspect.
I'm also suspicious of any prediction that predicts that things suddenly change for the much worse, and then leave it at that.
It can be very good motivation to extend negative trends, or to estimate when a system would collapse, if everything continued the same. But that really has much more to do with motivation to act now than it has with any valid prediction of the future. Much more interesting is to work on what we're going to do INSTEAD of the dreadful possibilities we can see happen if we did nothing.
Human beings will, when they have a choice, naturally choose the options that work better, rather than the options that work worse. There is the matter of seeing what the possibilities are, of course.
But, the moment somebody sees the negative consequences of continuing things unchanged, and the moment somebody notices that the current scheme isn't working, at that time things start changing for the better. Simply noticing that things won't work the old way will start one looking for the new ways.
The new ways are always there, waiting to emerge.