There's a huge difference in viability & mitigations here, though. In a shared metal system a portsmash attack isn't likely to be practically viable, and worst case is sched affinity or similar is used to just firewall off processes from co-inhabiting the same physical core. Kernel scheduler could even do this in a clever way, this has a very clear path to which it is basically fully mitigated.

So all signs point to shared metal still being viable security-wise, with mitigations either already deployed or pretty straightforward. Shared hardware will remain totally fine.

Shared-process, though, nobody is really talking about making that viable from a security perspective.