Re: you make a big assumption that our descendants will be the ones to play with the dangerous stuff and that they will be more intelligent for some reason.

I doubt it. You are probably misinterpreting what I mean by "our" or "descendants". Future living organisms will be descended from existing ones - that's about all I mean.

Re: That seems to acknowledge the intelligence / nanotech race condition that is of so much concern to singularitarians.

I figure we will have AI before we have much in the way of nanotechnology - if that's what you mean.

Building minds is much easier than building bodies. For one thing, you only need a tiny number of component types for a mind.

However, rather obviously the technologies will feed of each other - mutually accelerating each other's development.