According to a report from DonanimHaber, the launch of the GeForce GTX 660 Ti, GTX 660 and GTX 650 from NVIDIA will see the discontinuation of the GTX 560 and 550 shortly before the launch itself.
This is not usual, but when you start seeing the stock dry up on the GTX 560 and 550, you'll know its nearly 660, 650 time. So if you're looking at grabbing a new GeForce GTX 560 or 550, we would suggest waiting it out for a little bit.
The new 660, 650 GPUs are expected sometime in August-September, so if you're content with your system now and can just hold out for a little bit longer, it might pay off. You could also grab a GTX 560 or 550 cheap if someone is moving on up, too.