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.