I do wonder about single address space, I've seen a few experimental systems follow this strategy lately and it feels reliant on hardware less defective than we presently have in commodity user gui performance systems.
OS/400 and successors don't run on this kind of hardware.
https://developer.apple.com/documentation/security/preparing...
Meanwhile Google is doing the homework for Android.
"[Arm DevSummit - Ecosystem Talk] Improving Your Android App to Prevent Security Vulnerabilities"
https://www.youtube.com/watch?v=zkoOD4hmiGE
And regardless of one thinks of Oracle, Solaris SPARC has had it for ages.