eDRAM is absolutely a thing. The argument against it used to be that it had higher cost per bit, but who knows whether that's true anymore with the current bottleneck in dedicated DRAM chip production.

As an aside, if DRAM costs stay higher we might also see renewed interest in other memory technologies (especially persistent ones) such as phase-change PRAM and magnetic MRAM that sit between DRAM and mass storage in the memory hierarchy.