I'm not so sure about this tbh, to crop to 50% and give a further 2 x crop factor you would cut resolution to 1/4 meaning that the FZ1000 would have roughly 5mp vs the 9.7mp of the FZ200. Of course, resolution is not the only factor in IQ though.
FZ1000 image dimensions 5472 x 3648 = 20mp approx. 50% crop = 2736 x 1824 = 5MP approx
However, if you did a 1.5x crop so that focal length of the FZ1000 equaled that of the FZ200 then MP would be roughly the same (FZ1000 about 1MP less). I wouldn't like to guess which would give the cleaner images, the larger sensor of the FZ1000 or the f2.8 of the FZ200 at the long end in this example.