Now? Probably not too much, they have enough investment, and additionally talented people wanting to join. I mean, Andrej Karpathy also joined and left OpenAI twice and it didn't impact operations much.
I think OpenAI is now where Google was at or just before its IPO, a few key players leaving isn't going to impact them as much as it would have in its earlier founding days, and there is plenty of talent who are ready to jump in to fill the shoes of anyone who leaves.
https://www.ftc.gov/news-events/news/press-releases/2024/04/...
After this change they will have only one.
Via the FTC link:
"Existing noncompetes for senior executives - who represent less than 0.75% of workers - can remain in force under the FTC’s final rule, but employers are banned from entering into or attempting to enforce any new noncompetes, even if they involve senior executives. Employers will be required to provide notice to workers other than senior executives who are bound by an existing noncompete that they will not be enforcing any noncompetes against them."
Not actually sure how much Ilya was doing in the end, but clearly he did a bit, so it's likely a big a loss whatever way you look at it.