It would've been interesting to see the Corsair and Hellcat with a wing that is both of lower area and thickness - less 'carrier friendly' (say, for Marines and RAF/RAAF/RNZAF), but with greater level speed and range.
Reducing wing area probably wouldn't be as important as airfoil profile. It might even be that decreasing thickness:chord ratio at the expense of increasing area could reduce transonic drag and increase critical mach. Even doing this only at the thickest portions of the wing (near the root) could have been significant. Adding leading-edge extensions (possibly using a sharper leading edge and different airfoil type as well) at the roots and extending the oil cooler intakes could be significant in this regard. (similar in shape to the P-51's roots or the Me 262 HG-I's wing root extension, or possibly extending both the leading and trailing edge similar to the P-80 or F9F)
Wing extensions around the central pod may have helped the P-38's mach limiting problems as well given both the thick airfoil section and high speed flow inboard of the nacelles. (not sure if such would help the P-47 as much, short of a total wing redesign using thinner airfoil along the full span, or extending the chord along the full span to similar effect -that may have been more useful than the P-47N's extension, though probably a bigger production shift and more valuable had the P-47J's cowling been adopted)
This is something I've wondered about early Jet aircraft as well, particularly cases where a modified straight wing might have been simpler to adapt to the existing airframe without more substantial redesigns like the F-84F and F9F Cougar. Extending the chord of the existing wings seems like a more straightforward structural redesign than making the existing wing thinner (more like the F-94C adopted) given internal stores capacity (which might be increased), mounting/spar arrangements, etc. Plus, some degree of leading edge sweep or low degree delta planform is possible (granted, that would be more incidental prior to formal swept wing research data). I do recall engineering drawings of Gloster Meteor derivatives with leading edge extensions making it more of a delta shape, including the P.262 also employing a slab tailplane.
Plane Talking - HyperScale's Aircraft Scale Model Discussion Forum: Gloster Meteor question
http://i729.photobucket.com/albums/ww291/joncarrfarrelly/GLOSTER_P262_P300_01.png
You don't need swept wings until you are way-way over 400mph so I don't know how much good this does for propeller driven aircraft.
Doesn't that depend somewhat on the airfoil thickness and profile used? Very thick wings could have sweepback much more useful at lower speeds, but I suppose the counter-argument would be towards how many of those aircraft would just be better off with larger area, broader chord wings with thinner profiles in the first place?
Now do you build your planes like a Bf 109 so you can change wings with the plane sitting on it's own landing gear or do you need a crane to hold the fuselage up while a "new" wing with it's own landing gear is wheeled underneath?
Does each fuselage get two sets of armament if wing guns are used or do the armorers/mechanics have to swap the wing guns back and forth?
You could also have wings swappable outboard of the roots/landing gear (more like the Hurricane) rather than just at the fuselage or avoid the use of a crane by including strong points under the fuselage to be supported by jacks or support struts, or dollies of some sort.
That said, the whole idea of wings being (standard) swapped in the field seems a bit impractical. Having a fairly modular design with different variations assembled at the factory would make more sense, but even then having changes like wing chord extensions would be problematic in terms of matching wing-fuselage boundaries and proper wing fillets. (still potentially much greater parts commonality than completely different aircraft) And in the case of something like the Hurricane, it would be the outer wing portions that would be easier to replace, and the thick root section might be more practical to extend the chord of to make any new airfoil profile changes.
It may also eventuate that one wing becomes clearly superior in nearly all applications and becomes the new standard.