If you squint hard enough, the underlying object capability system as privilege boundary concept still does live on. In hardware the 432 went on to inspire 16

If you squint hard enough, the underlying object capability system as privilege boundary concept still does live on. In hardware the 432 went on to inspire 16 and 32 protected modes on x86. There it was inspiration for just about anything involving the GDT and the LDT including fine grained memory segments, hardware task switching of Task State Segments, and virtual dispatch through Task Gates. But a large point of the RISC revolution was that these kinds of abstractions in microcode don't make sense anymore when you have ubiquitous I$s. Rather than a fixed length blob of vendor code that's hard to update, let end users create whatever abstractions they feel make sense in regular (albeit if privileged) code. Towards that end the 90s and 2000s had an explosion of supervisor mode enforced object capability systems. These days the most famous is probably sel4; there are a lot of parallels between sel4's syscall layer and the iAPX432's object capability interface between user code and microcode. In a lot of ways the most charitable way to look at the iAPX432 microcode was as a very early microkernel in ROM.