He's the reason I started watching the show... so... yeah...

I don't see Michael Weatherly willing walking away. In interviews, I've seen him say that it would be hard for him to "stick a fork in Tony and call him done". So that gives me hope.

I can't see him, Mark or Paulie leaving.

Of course the Director is my first pick because I'm just not in tune with her character. Then (even though I hate to say it) Ducky would be next. After that, it gets kinda fuzzy with Tony being at the end of the list.