I'm going to go on a little bit of a rant here, and some people might not agree with me:
First, there is no absolute proof to the statement that the Mall game stores will stop selling PC Games outright. Even if they scale back further, they'll still keep in the high profile titles. It's not like EA is going to stop making PC games, Doom III, Half Life II, Unreal 2004, Serious Sam 2 (well I had to put that one in there becasue I really dig the game, and there is a sizeable fan base/mod community) aren't going to be console exclusive, small developers/publishers will still be making jewel box only value titles, and hopefully you can see where I'm going. There'll always be a market for PC games, but the Mall retailers with limited space must decide what they will make the most from with their allotted shelf space. (And most PC games don't carry as high of a profitability factor as most console games, hence why I had an almost impossible time finding a copy of Will Rock in a store).
PC games are the hosts for innovation. There are things that can be attempted on high end PC specs that may not be available on consoles, especially for the smaller developers who can't get a dev. kit for a PS3, XBX2. Also in terms of development, there is a much more minimal cost, and there are no licensor restrictions either.
Another thing about PC games is that they are able to partake in innovative distribution systems, like downloading, time-frame specific rentals, and what ever else may come down the line. Distribution systems like these are only in their infancy with consoles, and that is mainly because of X-Box live.
There is no argument that the Console market is more prevelant than the High End Gaming PC market, but the Casual Games PC base CAN be more prevelant, it really comes to the scope of marketing. However PCs are much more adaptable to new technologies than consoles (new graphic chipsets, online applications, etc).
Even if the mall stores dramatically scale back, PC games can still be bought at the stores that carry hardware, online, or at PC shows. The PC Game market is far from dead.