A company moving away from Nvidia/CUDA while the field is developing so rapidly would result in that company falling behind. When (if) the rate of progress in the AI space slows, then perhaps the big players will have the breathing room to consider rethinking foundational components of their infrastructure. But even at that point, their massive investment in Nvidia will likely render this impractical. Nvidia decisively won the AI hardware lottery, and that's why it's worth trillions.