It seems to me that fast cheap A/D, storage, processing power, and
memory take us to the place where commercially mainstream hardware can
implement a software defined radio where one or more whole bands or
frequency segments can be recorded to storage media, much like a TiVo.

Of course, the ability to convert b - (b+K) Mhz to 0 ... K Mhz and
sample at 2K Mhz, has been technologically possible for quite some
time now, but also quite expensive.

So my question is: how long before some high-end manufacturer of
either scanner, SWL, or ham gear introduces the ability to record a
band segment and "replay" the whole segment to let you tune into any
signals in the band at will from the recording?

Has it been done yet? If not, I wonder how long it will be.