> «Memory technology» as in «a single tech» that blends RAM and disk into just «memory» and obviates the need for the disk as a distinct concept.

That already exists. Swap memory, mmap, disk paging, and so on.

Virtual memory is mostly fine for what it is, and it has been used in practice for decades. The problem that comes up is latency. Access time is limited by the speed of light [1]. And for that reason, CPU manufacturers continue to increase the capacities of the faster, closer memories (specifically registers and L1 cache).

[1] https://www.ilikebigbits.com/2014_04_21_myth_of_ram_1.html