These days there's a crossgrader that can switch from 32-bit to 64-bit -- and apparently, if you're feeling lucky and know what you're doing, from amd64 to arm6

These days there's a crossgrader that can switch from 32-bit to 64-bit -- and apparently, if you're feeling lucky and know what you're doing, from amd64 to arm64, assuming you're going to take the disks and move them to a new system.