Here is a comment I copied from Hacker News:

If they join Sam Altman and Greg Brockman at Microsoft they will not need to start from scratch because Microsoft has full rights [1] to ChatGPT IP. They can just fork ChatGPT.

Also keep in mind that Microsoft hasn't actually given OpenAI $13 Billion because much of that is in the form of Azure credits.

So this could end up being the cheapest acquisition for Microsoft: They get a $90 Billion company for peanuts.

[1] https://stratechery.com/2023/openais-misalignment-and-microsofts-gain/