It'll become more common, especially if the 360 keeps picking up PC games the gap will become more apparent. The technology bar is rising pretty fast again (thanks largely to directX 10 hardware becoming more affordable).
Say if the 360 grabs a game like Crysis, it's going to have to sacrifice something and resolution will be the first to go, it's generally what happens every cycle. Consoles rule for a while, then tech outruns them and PCs are back on top.
This cycle will be especially interesting because instead of the usual bloom or shader or lighting upgrade, it's complex calculation, which opens a huge door for gaming. I imagine the PC will see a big revival once everyone starts catching up sort of like they did in the late 90s with all the new design possibilities.
It's one of the bigger reasons the tech difference between the 3 consoles doesn't bother me, compared to the massive jump dx10 they're all just fighting over scraps in the visuals department.
In a lot of ways it makes me happy, because I would like to see more games concentrate on art design than pure realistic graphics. I think Psychonauts was a great game for demonstrating that art direction will carry a game much further than very temporary technological power.
CS is a nice example of a game that went the realistic route, it looks laughable now, as where TF2's graphics will have a charm that far outlives the technology.
3rd Party Wall of Shame
http://www.nintendoworldreport.com/forums/index.php?topic=30478.msg581036#msg581036
