Team Fortress 2 has it's own style of art, which is quite similar to a comic one (many articles reported about). Though,what would TF2 look like with another one, let' say... with the Cel Shading look? Which is often used for games, that should have a comic look. Famous examples may be  XIII, Prince of Persia and  The Legend of Zelda: The Wind Waker.

Precisely this question posted the user "Knucklesx" to himself in the Steam forum (Thread) und began doing a graphic mod, which is supposed to implement exactly this idea. Unfortunately, beside some screenshots and a bunch of change notes, there have been no more updates.

“Whipped these up in a few hours. Shame they don’t work on sv_pure servers though. Should i do the rest of the classes?”

und

“Finished the classes and done the first person models. Except i tested them in a large game and the fps wasnt so good with them. since they are double the polycount of the normal models.”

 But, take a look at yourself and draw your own comparison

One possibilty,why there haven't been any more news,may be the issue of the number of polygons, which would be as much again. Although, yet another user named "FireSlash" gave a solution:

Maybe there is a well-informed modder in the TFPortal.de community, who is able to realize such a mod. Anyhow, it would be very interesting seeing this mod in action.