>The underlying scaling needed to go to 32 bit requires only linear progress to get to 256
Nope. Firstly, for RSA you need to scale from 32 to 4096. Secondly, Shor requires N^2*log(N) quantum gates where N is number of bits in the integer, so the scaling is superquadratic. And it's very much an open question whether QEC protocols will continue to work with the same efficiency on the required scales.
Nope. Firstly, for RSA you need to scale from 32 to 4096. Secondly, Shor requires N^2*log(N) quantum gates where N is number of bits in the integer, so the scaling is superquadratic. And it's very much an open question whether QEC protocols will continue to work with the same efficiency on the required scales.