How about 16 big core and 4096 small cores that don't have speculative execution?
https://content.riscv.org/wp-content/uploads/2017/12/Tue1136...
Perhaps one day we'll talk about how many cores are allocated to a program rather than the other way around. OTOH even their chip will have shared caches. Spectre is achieved via speculation but communicates via side channel of the cache, so it's not clear this is a whole lot better.
What nobody wants to say is that the real problem is running untrusted code. They don't want to say it because Apps and JS are so many peoples bread an butter these days.
Course, in the context of the larger thread, I can't help but wonder how much more attack surface this would tend to create.
We could consider something like Tilera chips working together with privileged "general compute" chips, the same way as current machines work with separate GPUs as privilege "vector compute" chips.
On a related topic, I know someone who worked on CPU/FPGA hybrid architectures. The idea was to move processes between CPUs and FPGAs. Awesome stuff, realtime processes offloaded to the FPGA get to run completely off the CPU, with ridiculously low latencies. The issue is that you really have to design your code for it.