Good post, upvoted.

I think that your remark

But the fact that we don't know what exact point is good enough is sufficient to make this a worthwhile endeavor at as early of a point as possible. It doesn't require optimism -- it simply requires deliberate, rational action.

assumes a utility function which may not be universal. In particular, at present I feel that the value of my personal survival into transhuman times is dwarfed by other considerations. But certainly your points are good ones for people who place high value on personally living into transhuman times to bear in mind.