> 401k as a sane guaranteed retirement plan
401k's do not have any guarantee, even in theory. You absolute should have some retirement plan outside of social security (which is, after all, just a backstop for that failing.)
> I am hesitant to believe social security will look the same way it does today when I am retirement age in ~35 years.
Well, I’m old enough that I've been hearing that refrain for more than 35 years, and have seen the math on the necessary changes to bring revenue and benefits in to line even if no action is taken before trustnfund exhaustion, and I haven't seen any sign that the radical damages some people try to use the threat of trust fund depletion to gain support for will become politically viable, so I am relatively confident that SS will remain in a recognizable form well into the future.