Which most - there is most as in number of cores shipped, and most as in number of organizations who have a license.
The second I have no doubt you are correct - I know of several organizations that have licensed ARM just to ensure they have a long term plan to get more without the CPU going obsolete again (one company has spent billions porting software that was perfectly working on a 16 bit CPUs that went obsolete - there was plenty of CPU for any foreseeable feature, but no ability to get more). These want something standard - they are kind of hoping that they can combine a production run with someone else in 10 years when they need more supply and thus save money on setup fees.
The first is a lot harder. The big players ship a lot of CPUs, and they the volumes to make some customization for their use case worth it. However I don't know how to get real numbers.
The second I have no doubt you are correct - I know of several organizations that have licensed ARM just to ensure they have a long term plan to get more without the CPU going obsolete again (one company has spent billions porting software that was perfectly working on a 16 bit CPUs that went obsolete - there was plenty of CPU for any foreseeable feature, but no ability to get more). These want something standard - they are kind of hoping that they can combine a production run with someone else in 10 years when they need more supply and thus save money on setup fees.
The first is a lot harder. The big players ship a lot of CPUs, and they the volumes to make some customization for their use case worth it. However I don't know how to get real numbers.