Basically, I don't see much here to demonstrate that Campbell is "behind schedule" or even approaching bust status (reference to the name of the thread, not your words).
I will go through each name and give my thoughts,
Crawford - Yes, he was a slow developer. No denying this.
Miller - Miller had already played in some NHL games and tore up the AHL, had a .925 season at this point
Howard - Howard was playing decent in the AHL but was held up by Hasek and Osgood
Bishop - Took as long as crawford, but changed teams twice in the process. Not sure if you want to use this amount of time as a good example, as we probably won't keep Campbell this long.
Schneider - Had 3 solid years in the AHL by this point
Bryzgalov - Most likely would've played in the NHL in 04, but yes he was an older draft.
Smith - Had 2 solid years in the AHL at this point
Lundqvist - Was tearing up the swedish league from the point he was drafted until he moved until the NHL
Elliot - Had a decent AHL year at this point and a few solid years in college
Allen - Again, solid AHL starter
Dubnyk - Didn't impress until his 5th year, got nhl time in 6th year
Enroth - Solid AHL time
Anderson* - Old draft pick
Now, if you keep Campbell as an AHL exclusive for 2 more years, you only have Crawford and Bishop with the same amount of development time. I'm not sure Campbell has proven that he will be able to be a solid NHL backup next year, so where do you go with him at this point? Keep giving him basic contracts until he proves himself? I have
no doubt that he will
eventually live up to his potential, but if that takes another 3-4 years we may need to look into other options.