That is a good question, I have definitely contemplated it a bit on my end.
I think he stays on until post-2026 WC. There is just so much momentum with this program and he has an opportunity to take the men's team and cement it as a top 25ish team in the world. I also think Herdman will see the GC and Nations League as an opportunity to win something here, obviously, these aren't huge competitions but winning one would mean a lot to the fan base.
Once 2026 WC is completed my guess is he will want to try his hand at managing at the club level. The question becomes what level can he break into following his international success? He will be 50 following the 2026 World Cup, still plenty of time to take on a new project.