Kale chips -- nutritional value?

It depends on how the kale chips are made. If you use a dehydrator, it will not detract any nutritional value, but baking them in a hot oven will. I'd say that it is not a significant difference to eating raw kale, considering that our stomachs cannot completely break down the raw roughage and extract every single vitamin and mineral. Any kale is good for you!

It cannot possibly be worse than kale that has been stewed to death...

I think the difference is very insignificant.

I don't know the definitive answer, but I can't imagine that it would harm the nutritional value any more than sautéing or steaming it.