OpenAI is far from being self-sustainable and without significant external investment they'll just probably be soon overtaken by someone else.
Here's something I feel higher confidence in, but still don't know: Its not obvious to me that OAI would be overtaken by someone else. There are two misconceptions that we need to leave on the roadside: (1) Technology always evolves forward, and (2) More money produces better products. Both of these ideas, at best, only indicate correlative relationships, and at worst are just wrong. No one has overtaken GPT-4 yet. Money is a necessary input to some of these problems, but you can't just throw money at it and get better results.
And here's something I have even higher confidence in: "Being overtaken by someone else" is a sin worthy of the death penalty in the Valley VC Culture; but their's is not the only culture.