Wither 64 Bit A/D?

Why is the Analogue to Digital process described at 32 bits(for some
ADC chips) and seemingly no such specs for RF DSP, anyhow how exactly
one hope to achieve 64 Bit A/D since there’s 128Bit DSP boards about.
one build a set of ganged ADCs such as 4 * 16 Bits or 2 * 32 Bits? What
is the best way to get hign bit rate conversion on paper?