Memristors versus bubble memory
Regrading memristors going to the wayside like bubble memory, maybe. But the problem bubble memory had was it was trying to compete mainly with hard drives, and they became faster and cheaper than bubble memory. Bubble memory stayed on in applications that required ruggedness. Later on, when flash came out, it was so much faster than bubble memory that it displace it in the remaining markets.
Memristors? The big problem was to discover and develop them to begin with, which has been done. The manufacturing techniques appear to be quite conventional, they've been ramped up already to 1ns speeds, and should use less space per bit than flash (so it should be cheaper than flash), and no write life limit. I would not have guessed flash would have taken off as much as it has, given how much more costly it is than conventional hard disks, but it has -- and I think that is going to be memristor memory's competitor rather than competing with hard disks.