Kind of seems like we should be making chips with both. Big HBM stack on top as a sort of huge L5 cache like thing. And then a bunch of DRAM type sockets (like LPCAMM) around the exterior.
[edit] The packaging needed to support HBM is also much more expensive too. If demand for current HBM applications tanks and the manufacturing lines need filled, then maybe. Currently, the price point would make it very very niche.