Why not try to have them switch you to UA760 DEN-MUC non-stop? They might not be willing to change origin to FSD since SUX flight is still in schedule, but they should be willing to put you on DEN-MUC flight without charging more miles due to the schedule change. There's also an LH DEN-MUC flight, but opening up inventory on partners is generally more challenging. If you SUX flight gets pulled eventually, you could then try switching to FSD.