After digest information about IBM 360, I decided, we lost CISCs. One of most important feature of 360 was customizable microcode, which you could load on system boot and got effectively different hardware (like with FPGA emulators of Amiga's). It was widely used to emulate old hardware, like IBM 1401 or IBM 7xxx series. But I have not seen this feature in 390 documentation, so looks like their 360 emulation become just software (and with achievements of semiconductors in 1990s it looks like adequate, to switch to software emulation).
This was not only feature of 360th, for example Xerox Alto, also have documented feature to alter microcode when need (as I hear, they have special framework to work with it, just like we now work with Assembler when need), and I hear rumors that something similar was shipped with DEC mini-computers, but for micro-computers, this feature practically disappeared.
Even when we have "microcode update" feature in many modern CPUs, but it is usually undocumented feature, to which nobody have access outside CPU manufacturers (only could upload encrypted binary, supplied by manufacturer to fix bugs). As I said, in 360th, this was documented standard feature, you could use if need.
I must admit, ARM marketed feature of customized microcode, to add new instructions (they have standardized place in instruction set, named "custom coprocessor instructions", so if you have enough money, you could make special ARM with your additional instructions, you could even order some additions on die), but it is nothing if compare to 360.
And I could tell from FPGA cooking, not all things implemented in FPGAs as hardware logic pipelines. When speed accepting, many people using in FPGA practically microcode engines (very common thing is 1-bit CPU, which is very similar to CISC microcode engine, and programmed in Assembler, very similar to early 8-bits; some people prefer full-featured CPU, like 8048 or even more).