ARM and Microsoft don't "care" enough to do anything beyond a bit of token research. Maybe there will be some extremely niche chips one day, or maybe not because the problem can be solved 90% as well in software on ordinary hardware.
Not to mention the smartcard market which would mean billions of processors around the world.
Smartcards often run Java Card, which solves the whole memory safety problem the other way around. You don't need CHERI for this kind of limited platforms: want to run memory-safe C today? Just ban all dynamic memory allocations. Throw in the usual UB restrictions and stick to a single thread and very little can go wrong.
What's important to remember is that, despite its large deployment figures, those are still niche applications. The number of people developing for them is a rounding error. There is no clear path from there to mainstream adoption.
We don't need to measure technology adoption by the late stage capitalism of Silicon Valley VCs.
Many technologies do leave an impact in the industry even when adopted in niche domains.