To address the memristor existence questions: if you define a memristor as a device which "remembers" its resistance via a pinched hysteresis I-V curve, then we

To address the memristor existence questions: if you define a memristor as a device which "remembers" its resistance via a pinched hysteresis I-V curve, then we have had ReRAM/ memristor devices for some time now. On the other hand, if you define memristor as a device with coupling between charge and flux, then no. Practically speaking, it's unlikely that memristors will replace transistors because they're about 500X too slow and have about a billion times less endurance. Same issue with memory replacement. They could in theory make excellent flash memory replacement, but currently sneak paths, thermal crosstalk and ion crosstalk remain challenges