Old idea, except Flash is far from ideal for this purpose. Old, because this is the ultimate use of something like memristor and has been discussed in that context before. Flash is non-ideal, you still have to do wear levelling, else it wears out.
Now if HP ever did finish off memristor, or if any of the other players in that new-memory-tech game got their act together, that would be ideal. Faster than DRAM, great, non-volatile, check, wear-free lifetime, perfect. It'd be just like a SIMM that doesn't forget, ever.