Speculation is just a kludge trying to speed up a legacy architecture. It is possible to obtain speed even without speculation, just not without some other fresh ideas.
For example the vaporware Mill architecture is in-order on the CPU level but compilers can optimize to run code very concurrently.
yeah, my thinking is we are to focussed on the current state-of-the-art approaches (i.e ooo superscalar, ht, memory architecture etc) where we can eek out the last few % of performance. I wonder if doing something radically different, would have a different tradeoff for performance vs security/trust.
For example the vaporware Mill architecture is in-order on the CPU level but compilers can optimize to run code very concurrently.