Uh, you have to go to the experts in ID. Or, perhaps you have found a major flaw in ID?
I just don't see that the assertion that "certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection" requires belief that God is dead. It makes no sense.
ID doesn't specify who the designer is so I see no connection between that and belief in God's continued existence. Nor do I see that questions about the designer's continued existence are relevant to the assertion.
The aspects of the universe that are best explained by design are still there, whether the designer is or not. The best statement that it can make is that the designer existed (past tense), just like your posts on FR indicate that you were alive today, even if you were to die tomorrow. They reflect that you existed, not that you continue to exist after you stop posting. So if you stopped tonight, a year from now no one could make a reasonable guess on your continued existence based on your posting history, they would just know that at one point in time, you did exist.