ARM does not have a 'ibm pc clone' moment. There is no one, that anyone wants to rally behind. The market is fragmented in an interesting way but a way that is hard for people to target. This fragmentation has existed since the start of microprocessor was started. There were hundreds of different x86, 6502, SH, MIPS, ARM style computers as well. Even the 'ibm pc' was even one of them, but everyone just kinda said 'that one'. All of those standards you said exist in some ARM boards. It is a really mixed bag. Out of all of the ARM systems RasberryPI came closest to a standard.

QCOM in this case probably could make a standard ARM PC. The problem will be QCOM corporate structure will probably strangle it. They will want to create a patent license stream. The interesting bits would be behind NDAs. It is their bread and butter.

The reality is no one wants to be IBM in the IBM/PC clone market. Basically the ones who did the expensive work to make the board but everyone just copies it.