One such developer: I love CUDA, even if I don't like Nvidia. CUDA is the most direct and transparent way to work with the GPU for the stuff I do and it is on account of it not being an open standard: it doesn't have four vendors trying to pull it their way ending somewhere in the middle and it has been very stable for a long time so I don't need to update my code every time I get new hardware, though sometimes some tweaks are required to get it close to theoretical maximum speed. That alone stops me from going with an 'open standard' even though I'm a huge fan of those. But in this case the hardware is so tightly coupled to the software I see no point: there isn't anything out there that would tempt me.

So, locked in? Yes. But voluntarily so, I could switch if I wanted to but I see absolutely no incentive, performance wise or software architecture wise. And the way things are today that is unlikely to change unless some part is willing to invest a massive amount of money into incentivizing people to switch. And I'm not talking about miners here but people that do useful computations and modeling on their hardware, and all this on Linux to boot, a platform that most vendors could not care less about.