It seems we have been missing the cabbage merchant lately. I think he'll show up at the very end. My theory:
A few months after the war has ended, everything is bright, sunny, and hopeful. The kids go back to Omashu to play on the delivery slides (for old times sake). Things go horrible wrong, they crash into his cabbage stand, and you get the picture.
But then again... He just may not come back.
The cabbage merchant is my favorite nonimportant caracter (next to Hope and Foam Guy). I really do hope he makes an unexpected appearance.