The key for PC gaming is the advancement in mobile capability and the open platform. Since this generation of consoles was launched, laptops went from a very expensive internet browser with some word processing/spreadsheets/presentation programs with very little gaming (unless you spent a ton) to capability close to that of a desktop for relatively cheap. That right there increases PC gaming when the next round of consoles come out.
You have to look at why consoles are king right now. In 2005, in order to have a gaming PC you needed to spend at least $1000 on a desktop along with peripherals and the whole 9 yards. Big money. A console gave you a smaller package with simple controls for 1/2 the cost. So tons of people have consoles because the alternative was poor. Since people already have the consoles today, that market share is really high even though the they lack the capability of today's PC.
Now it's a whole different world. Current laptops with on board graphics are coming close to the capability of the current consoles, and for relatively cheap. Heck, there are even cheap laptops with GPU's that surpass consoles, and with tech like Optimus they even get good battery life so getting a discrete GPU is not as big of a hassle. These things are stuff people already own in huge numbers, and was not true 5+ years ago. When people are faced with buying another console, they now have the option of saying "hey, I already have a machine that plays games really well. Why do I need a console?" That is one thing that will change PC gaming. It effectively flipped the script. Sure, laptops might not have the capability of a new console, but just like the consoles of today there is a built in user base. People will put up with less if the buy in is zero. This is something consoles companies never mention when people ask why they drag their feet on the next console. They have a huge built in userbase, and if they upgrade they lose it in an environment with 10 times more alternatives than the last time they launched a console.
Just look at handheld gaming as the predictor. Phone gaming is killing the handheld market even though they are not dedicated gaming machines. With more people having gaming capable laptops and tablets, the next gen consoles face a huge battle.
The next is the open platform. With mobile games becoming more and more popular, people will look for the ability to share them across platforms. Consoles don't do that, PC's can and do. As the lines blur and more people own PC's, the consoles become the niche market, not the PC.
Consoles are just too pigeon holed into one thing to thrive in the coming decade. The only way they will be able to do it is essentially becoming a PC, and then the line is gone.