IMO the first step would be disclosing all their tricks they implement outside of the specs they give. If researchers had adequate documentation of all the side effects that these tricks introduce then it could be properly audited.
Looking at how they behave the only thing I would expect from them is to not give free shovels when people are trying to dig. They will keep turtling until there's a new product they can push and rush everybody to ditch the "insecure predecessors".
Something like adding "Implicit caching occurs when a memory element is made potentially cacheable, although the element may never have been accessed in the normal von Neumann sequence. Implicit caching occurs on the P6 and more recent processor families due to aggressive prefetching, branch prediction, and TLB miss handling." to the developer's manual.