The pre-open market doesn't see it as a big win for MSFT. The stock is still lower than it was at Friday's open.
Best case scenario for MSFT probably would have been to negotiate Altman et al back to OpenAI with some governance changes to boost stability. Keep the OpenAI GPT-N momentum going that they have harnessed for themselves.
MSFT have managed to neutralize (for now) the threat of Altman et al creating a competitor, but this has come at the cost of souring their relationship with OpenAI who they will continue to be dependent on for AI for next couple of years.
Big question here is what happens to OpenAI - can they keep the momentum going, and how do they deal with their sugar-daddy & compute-provider MSFT now also being a competitor? How much of the team will leave, and can they recover from that ?
What would cease to exist would simply be speculation and arbitrage. Since all prices are perfect, you simply wouldn't be able to make more (or even less, for that matter) money than the return on capital everyone gets by buying and selling shares quickly.