I think - and hope - that NdJ won't be too missed in the semis. Against Uruguay a midfield combo of van Bommel, Sneijder and van der Vaart should be more than sufficient. Van der Vaart is quite capable of taking a defensive responsibility as well, and offers more than NdJ going forward. I would actualy have prefered him in the team over NDJ against lesser teams in the beginning of the tournament.
That said, if Holland make the final, NDJ will be needed against Spain/Germany.