As long as we're speculating, my two cents: I do think that reference class forecasting is a valid way to predict the magnitude of change if not the direction, but I don't think that using reference class forecasting necessarily implies "business as usual".
1) In my view, the intelligence explosion already happened, with the invention of writing. It will continue to happen, faster and faster as exponential growth does. There's no reason to posit that there will be a qualitative change in this trend. Any developments in AI, etc... can all be taken together as part of this explosive trend and not as a singular exceptional event.
2) Reference class forecasting says that the business-as-usual future is very unlikely. Hunter-gatherers would not consider our current lives to be "business as usual" at all...I can't imagine they would have any idea why we do the things we do. Primitive agriculturalists with writing would find us slightly more familiar (our concepts of property, marriage, the notion of formal schooling, formal warfare, wages and labor, heirarchy, etc) but our more futuristic edges (the notion of science, the sheer scope of technology) are probably still pretty hard for them to understand. I think there are lots of qualitative divides between early-return hunter-gatherer, late-return hunter gatherer agricultural, industrial, and information age societies which make it hard for them to understand each other.
I'd say that reference class forecasting might also predict that the more privileged, tech savvy among us shouldn't expect to be completely shocked within our natural life-spans. Historically, this is probably only true for a privileged subset of people. I imagine a lot of the more isolated hunter-gatherers and subsistence agriculturalist groups were, are, and continue to be rather abruptly shocked as they come into contact with modernity.
I agree strongly with 1), with the addition that another one happened in the modern era when engineering prowess, military strength, and highly versatile, effectively truth-seeking science and philosophy finally coincided in Europe and Asia.
I suspect that if neither the singularity nor a disaster occurs, there is likely to be a different huge shift, probably focused around a resurgence in the power-and-control super-science that defined Victorian through Space Age technological advancement, or alternatively in some form of social sphere.
I'd also add that...
What, in a broad sense, does the future look like? We don't know, and while many have historically made predictions, the track record for such predictions is less than impressive. I have noted that there appear to be two main types of view about the future-- the "new future" and the "business-as-usual future." In order to simplify this discussion, let's restrict it only to the coming century-- the period between 2013 and 2113.
The "new future" is, generally speaking, the idea that the coming century is going to be very different from the present; the "business-as-usual future" is, generally speaking, the idea that the coming century is going to be very similar to the present.
Here are some characteristics of the new future:
Here are some characteristics of the business-as-usual future:
Reference class forecasting seems to indicate that the business-as-usual future is quite likely. But as we know, this is far from a textbook case of reference class forecasting, and applying such techniques may not be helpful. What, then, is a good method of establishing what you think the future will look like?