That is going to look great!
I love nubuc and have been looking for another flap bag in green like this or purple (I've seen some lately but they've been too expensive or sellers won't ship internationally or will only ship through the GSP )
I dunked a burgundy nubuc back pack a while ago and have been been meaning to post after shots. I sanded the handle which was really dark and yucky and I'm really pleased with the result. I also spot dyed a few spots that had worn and were looking whitish.
I think Whateve's suggestion about spraying it with scotchguard or similar is good, though I've found that my rose pink nubuc flap is remarkably resilient and even when she got some colour transfer from my jeans I was able to remove it easily with the eraser and brush.
Here's the before pics. I'll post the after pics this weekend. Can't wait to see yours.
http://forum.purseblog.com/coach-clubhouse/coach-rehab-and-rescue-club-833400-59.html