Antonyms for the phrase "of that ilk" might include "disparate," "distinct," or "unrelated." Whereas "of that ilk" suggests a close relationship between two or more things, the aforementioned antonyms evoke a sense of divergence, difference, or non-association. Another possible antonym for "of that ilk" might be "dissimilar," which connotes a lack of similarity or resemblance. Alternately, terms such as "varied," "heterogeneous," or "diverse" could also serve as contrasting or opposite ideas to "of that ilk," suggesting a range of disparate or distinct possibilities rather than a homogeneity of likeness or sameness.