Here's what I did upon hearing the news: booked a SQ F award to replace a CX award I had already reserved (luckily, through BA so the avios refund won't cost too much). Chase card will be cancelled imminently.
And I'll be looking for additional ways to burn my remaining miles ASAP, ALL on *A partners. Looks like my parents will be taking that Australia trip they've always wanted. Not a single mile will be spent on UA awards, and my future loyalty is gone. Now I've never gone above 60k miles/year on UA metal, but look for that to drop. What's the point?