I live in DTW and there currently is no talk / hype about an ice storm on Sunday/Monday. Sure they're calling for some variety of precipitation on Sunday and Sunday night, but it just sounds like some light mix of rain, sleet, and snow. Not calling for a big storm or more than the garden-variety winter precip.
Your flight will be fine.
Anytime they start having to cancel, they usually start with the regionals, canceling the RJs before they start slashing mainline, particularly to destinations like CUN.