Eliminating aging also has the potential for strong negative long-term effects. Both of the ones I’m worried about are actually extensions of your point about eliminating long-term value drift. No aging enables autocrats to stay in power indefinitely, as it is often the uncertainty of their death that leads to the failure of their regimes. Given that billions worldwide currently live under autocratic or authoritarian governments, this is a very real concern.
Another potentially major downside is the stagnation of research. If Kuhn is to be believed, a large part of scientific progress comes not from individuals changing their minds, but from outdated paradigms being displaced by more effective ones. This one is less certain, as it’s possible that knowing they have indefinite futures may lead to selection for people who are willing to change their minds. Both of these are cases where progress probably *requires* value drift.
It appears to be the extrapolation using exponential growth from current capacity using maximum likelihood to fit the growth rate. Whether you believe the date comes down to how well you think their generalized logical Qubit measures what they’re trying to capture.
I think it’s worth remembering that asking experts for timelines requiring more than 10 years often results in guessing 10 years, so I would tend to favor a data-based extrapolation over that.