They have released a statement that he won't do any more for the U.S. version of RKN, but I know he has several American episodes shot that haven't been aired. So, there may be more coming, or they may just decide not to air them. They would be sold another way, though, if that happened.
I really hope the British version continues. It's great. Although they do, more and more, seem to cast the restaurant based on how certifiably insane the owners are.