I changed my seat last minute yesterday when checking-in online even though the seat next to me still showed as available (I was in the window seat of a pair) and the center seat was blocked in this row. I was gambling on the fact the flight shouldn’t be full and that if I did have a seat mate, they’d want to migrate. Hahaha yep I was right! The feet you see in the pic are of my would-be neighbor but thanks to my switcheroo I have the entire row to myself.