My best guess is that it's caused by poor quality solder subjected to high temperatures over multiple thermal cycles. Eventually fractures start to form in the soldered connections of the GPU to the board.
I don't know if "this exact period" is really the case. Problems have been reported for well over a year. But the frequency of reports does seem to have increased over the past couple of months. One would certainly hope that we're seeing the peak now.
Maybe. They have in the past. As mentioned above, it has only been a few weeks since this issue has caught the attention of some tech writers. That might put a little more fire under Apple's feet.
If they don't, I think the most appealing solution would be a reball (not reflow!) using lead based solder.
Something like this.
But my advice for now would be to wait a little longer to see if Apple makes a move. And if it's working well on the HD3000, I'd do more than "limit switching". I'd lock it down.