You've actually pointed out why the first thing won't really happen - PC isn't the only gaming platform, people won't buy a new £550 GPU for a 5-10% improvement, just like people don't replace their £300 CPU for a 10% improvement now.
Even if AMD do go under, it isn't like PC gaming has no competition and Nvidia still need to generate revenue so they will have to do that by delivering a reason to upgrade.
As thus forum shows.
people do
....