You'd probably have to find an Intel insider to know the real truth.
But the most likely possibility is that the plan was too grand for the time (note, this was 197x to ~ 1984ish, the IBM PC with its 8088 had only been on the market about three or so years) and therefore much too expensive for any market to bear.
Additionally, the iAPX432 was being worked upon during the same time that the IBM PC suddenly brought the x86 chips to significant popularity.
Combine the concepts of pouring money into an arch. that was too big and grandiose for the integration tech. at the time, with a sudden influx of profit from the x86 chip line, and it seems that a likely reason was simply to devote resources to the chip line that was suddenly producing those same resources.
"Using the semiconductor technology of its day, Intel's engineers weren't able to translate the design into a very efficient first implementation. Along with the lack of optimization in a premature Ada compiler, this contributed to rather slow but expensive computer systems, performing typical benchmarks at roughly 1/4 the speed of the new 80286 chip at the same clock frequency (in early 1982).[7] This initial performance gap to the rather low-profile and low-priced 8086 line was probably the main reason why Intel's plan to replace the latter (later known as x86) with the iAPX 432 failed. Although engineers saw ways to improve a next generation design, the iAPX 432 capability architecture had now started to be regarded more as an implementation overhead rather than as the simplifying support it was intended to be."
That makes sense. I remember absolutely huge data sheets and reference manuals for the IAPX432. So it's very possible that Intel didn't think hard about re-licensing the somewhat janky 0x86 design because they expected it to be a dead end.
Historically speaking, I'm not sure if Intel ever -wanted- to license x86.
The main reason that AMD (and others) manufactured x86 CPUs early on was because IBM had a 'second source' requirement; i.e. there had to be another vendor who could provide the same part.
So an AMD 286 was no different from an Intel 286.
By the time of the 386, IBM had relaxed/dropped the second-source requirement. Thus the Am386 isn't the same design as the i386 (and there was a court battle to try to keep the AMD part out of the market.)
Am386 was reverse engineered design, but microcode was 1:1 Intel copy :). There was no
court battle over this chip. Intel was forced into arbitration due to second source agreements, and lost.
Court battle was over 287 and later Am486. AMD announced clean-room design ... and gave their clean room engineers 386 microcode copy :]
But the most likely possibility is that the plan was too grand for the time (note, this was 197x to ~ 1984ish, the IBM PC with its 8088 had only been on the market about three or so years) and therefore much too expensive for any market to bear.
Additionally, the iAPX432 was being worked upon during the same time that the IBM PC suddenly brought the x86 chips to significant popularity.
Combine the concepts of pouring money into an arch. that was too big and grandiose for the integration tech. at the time, with a sudden influx of profit from the x86 chip line, and it seems that a likely reason was simply to devote resources to the chip line that was suddenly producing those same resources.
The Wikipedia page (https://en.wikipedia.org/wiki/IAPX432) also says this about the '432:
"Using the semiconductor technology of its day, Intel's engineers weren't able to translate the design into a very efficient first implementation. Along with the lack of optimization in a premature Ada compiler, this contributed to rather slow but expensive computer systems, performing typical benchmarks at roughly 1/4 the speed of the new 80286 chip at the same clock frequency (in early 1982).[7] This initial performance gap to the rather low-profile and low-priced 8086 line was probably the main reason why Intel's plan to replace the latter (later known as x86) with the iAPX 432 failed. Although engineers saw ways to improve a next generation design, the iAPX 432 capability architecture had now started to be regarded more as an implementation overhead rather than as the simplifying support it was intended to be."