For Microsoft, and the other hyperscalers supporting OpenAI, they're all absolutely dependent on OpenAI's success. They can realistically survive through the difficult times, if the bubble bursts because of a minor player - for example if Coreweave or Mistral shuts down. But if the bubble bursts because the most visible symbol of AI's future collapses, the value-destruction for Microsoft's shareholders will be 100x larger than OpenAI's quarterly losses. The question for Microsoft is literally as fundamental as "do we want to wipe $1tn off our market cap, or eat $11bn losses per quarter for a few years?" and the answer is pretty straightforward.
Altman has played an absolute blinder by making the success of his company a near-existential issue for several of the largest companies to have ever existed.