replace the keyboard with a late 2010 model or fix a wine drenched dot

First, salvaging the older systems keyboard to fix your newer system I think you'll find is not that easy. It would be just easier getting a proper replacement keyboard which are not that expensive.

As for trying to recovery your current keyboard. I'm sure the acids in the wine has eaten away at the contact & traces enough so the key is not fixable given the amount of time thats past. Sure its worth trying as long as you're not under a time crunch.

I would first see if popping off the key cap and using some distilled water on a cotton swab (Q-Tip) is able to get to the damage. If not removing the keyboard from the uppercase would be the only other way. While you would need to go this far if you where to replace the keyboard alone so if it fails to work you really haven't lost anything in the process. The only rub here is some of the keyboards are riveted Vs screwed or a combo of both. So while you might be able to salvage the keyboard you may not have enough fasteners to support the keyboard.

If you get a new keyboard make sure the supplier also gives you the needed fasteners with it.

Here's the IFIXIT guide to get to the bare uppercase: MacBook Air 13" Mitte 2011 oberes Gehäuse austauschen and heres a similar system guide on keyboard replacement: MacBook Pro (13 Zoll, Mitte 2010, Unibody) Tastatur Austausch jump to the last steps for reference.