Dear Laurence Hitterdale,
Thanks for a sober appreciation of the problem. I think the Singulartarians and other technology cultist's are simply exhibiting their complete misunderstanding of what consciousness is. They think it's an artifact that emerges from Lego blocks, so more and faster Lego blocks are all we need. Don't hold your breath.
And as you point out, no amount of life extension will amount to immortality, i.e., deathlessness. I tend to think that "it is implausible to suppose that the natural limits on technology are much tighter than they seem to be." But steady progress in technology will not yield transhumans, only greater efficiencies in most areas and, hopefully a few new lasers or MRIs -- even a new Internet. But technology won't make us gods. So I fully agree with your second strategic principle that we can rely only on human character and motivations as we now find them.
Finally I agree that you can't steer from outside, but only by steering yourself in the best direction you can conceive.
"Grand solutions, whatever they may be for others, remain only fantasies for me."
That is compatible with my essay, which I hope you will read and comment on.
Good to see you here again,
Edwin Eugene Klingman