Would a pipe wrench fit in there? Probably not...
Another solution might me to grind some new sides on the plug head with a dremel, grinder, cutoff tool, or even a hand file. Just 2 sides are needed to give a wrench another chance at it. Once you get a wrench tightly on it, whack it with a hammer to shock it. Hammer action is much more likely to break it free.
I'm interested in aquiring this new type of extractor, which looks ideal for this particular situation, but I have not tried them yet:
If nothing else works, I would next be inclined to drill it out.
Grease or teflon tape on the threads will prevent this problem. Most other cars have plugs with much shorter threads, so the motor oil keeps them moving well enough.
If you ever do get it out, consider a valve instead of a plug:
I would be concerned that those Topsider devices may not get out any 'heavy' material that has settled to the bottom of the pan. I do have one, and it is certainly great for auto transmissions without plugs, but I have chosen to use the valve method instead for engine oil.
Best of luck.