I would not give up on it. The challenge of getting that thing off there would get my full attention. I would likely try non destructive methods first then progress from there. In the end I would get that thing off there even if I destroyed the frame in process.

Actually, at least two very good methods of getting a good grip on the cup have already been described. Welding a bar to it or using a large bolt and nut should work for that part. The trick might be holding the frame in such a manner that it would not be damaged by the excessive torque required to remove the cross threaded part. I would save the "Victor Wrench" for last. I guarantee I could get the cup out of there one way or another, but the chances of damaging the frame would be huge. Of course the frame is very close to useless in it's present condition, so if it is damaged beyond use in the process of removing the cross threaded part, not much has changed. If not, the frame may be saved.