I've seen some articles that use the 100 game threshold for success, while others have done 200 games. I saw one that was 160 games because that is the point where they earn a pension.
As for the viability of individual draft picks, this was a good article (although a few years ago now):
Cullen: Updated NHL Draft Pick Values, Observations
Using this as some kind of scoring:
10 - Generational
9 - Elite Player
8 - First Line, Top Pair D
7 - Top Six Forward, Top Four D
6 - Top Nine Forward, Top Six D
5 - NHL Regular
4 - Fringe NHLer
3 - Very Good Minor Leaguer
2 - Minor Leaguer, under 50 NHL games
1 - 10 or fewer NHL games
The #9 pick ranks out at 5.03 on that scale.