The FZ200 has two advantages (of sorts) over the SX50.
1-the f2.8 stop
2-a much better EVF
The EVF on the FZ200 was my first experience of EVFs. I don't like it, period. If the EVF on the SX50 is noticeably worse, then that's a huge negative for me.
The big attraction of the SX50 is undoubtedly its 1200mm effective maximum focal length. However, the fact that the maximum aperture at 1200mm is 2 & 1/2 stops down from that of the FZ200 at 600mm equivalent, must have a significant effect on the usefulness of that 1200mm focal length on the SX50.
Even if the camera is on a tripod, all subject movement at 1200mm is magnified to a greater extent than at 600mm. Without a tripod, whether the subject is moving or not, the minimum shutter speed at 1200 for a sharp shot will be double that required at 600mm, assuming that both cameras have equally effective image stabilisation.
Instead of, for example, 1/640th exposure at F2.8, 600mm and ISO 100 with the FZ200, with 1200mm one would need to use 1/1250th at F2.8, and ISO 200, if the image is not static and/or if one doesn't have a tripod
But one doesn't have the option of F2.8 on the SX50, so one would have to use 2 & 1/2 stops higher ISO than ISO 200, which is between ISO 1,000 and ISO 1250.
At such high ISOs the SX50 shot is going to be rather noisy and degraded, which sort of diminishes the advantage of that 1200mm focal length.
I can't say the SX50 particularly excites me, but it would be interesting to see some comparisons between the FZ200 at F2.8, 600mm and ISO 100, and the SX50 at 1200mm, F6.5 and ISO 1250.
Another issue, of course, is the accuracy of the Canon nominated ISOs on the SX50. DXOMark have not provided test results for the FZ200 yet (rather slack of them), but the DXO tests for the FZ200's predecessor, the FZ150, show a remarkable match with Panasonic's nominated ISOs. They're 'spot on', implying that Panasonic are using the same standard as DXO.
If Canon are not using the same standard, the meaningful comparison might be between a 600mm shot at ISO 100, with the FZ200, and a 1200mm shot at ISO 1600 with the SX50.