Spot on summary. I guess who has faded the least since the first fight might also be a factor. Neither are what they were. Who's fallen furthest? My hunch is Garcia although he's been more active. If khan fought like he did against Kotelnik he'd have a chance of a points win.
Khan because he's a better boxer, has more speed and better footwork, should be more hungry, knows how Garcia fights and finally because he did earn every single victory in his record.
Probably the same result as last time. Khan gets an early lead by beating Garcia to the punch, and out working him. Garcia will look to time Khan and get that left hook in, like he always tries to. Eventually he will get it through and stop Khan not too long after that. Even if it's not a perfect shot on the chin (or neck), he'll land it often enough and eventually land in the right spot to drop Khan or really hurt him.