If Qualcomm is a relevant topic regarding ARM's success, then they've arguably already failed.
I'm not so sure it's the expensive large chips, made in relatively small quantities, that make ARM the most money, do you have a source? I'd have guessed they actually make more on the billions of small ARM cores that ship every year that end up by multiples in pretty much every device with a battery or power cord. And these, I think, are at the biggest risk of leaving ARM. RISC-V development is mature enough at this end of the market that it's relatively easy for users to transition, there are multiple competitive cores on the market, and there's no concern here about backwards compatibility because these are embedded systems where there's usually not an expectation of having to run user code at all. It will be much harder for the likes of Qualcomm where there's a huge ecosystem built around their ARM processors - but as a share of cost-per-processor, they probably stand to gain the most. Qualcomm is a founding member of the RISC-V foundation after all.
No, ARM is 100% owned by SoftBank. Apple sold their shares a while ago.
Overall ARM doesen't really make that much money, especially compared to some of their clients. It's not even obvious to me if would make sense financially even for Qualcomm to design their own RISC-V cores compared to licensing from ARM.
I mean they could and did design their own cores but they are still using ARM designed ones for their top-end chips.
Most of these firms are licensing a core from a third party. There is no such thing as ‘on their own terms’.
Or they believe that designing their own cores would be cost prohibitive and prefer licensing them from ARM.
It's also not obvious to me than licensing conditions for RISC-V could be more favorable than what ARM is offering. Why would you anyone even license competitive cores their competitors if they can make more money selling them themselves?
There simply isn't that much money in designing cores. The money is in selling SoCs or devices. Arm at least has made increasingly high quality cores available at reasonable prices to all comers. A future where Arm's business is made unviable is not necessarily better for consumers.
You can license RISC-V cores from Si-Five today but they if reports are correct they were in discussions to sell to Intel. If that were to happen who knows what would happen to their offering. There will be others of course but as you say it's not obvious that what they offer will be any better that what Arm offers today.
And for the foreseeable future Arm is immune to takeover by any of its deep-pocketed customers.
I'm very happy that RISC-V exists from a number of perspectives but there needs to be a realistic assessment of its potential impact.