I would just tweak your projections abit.
Top six forwards (hopefully & trending upwards):
Horvat
Baertschi
Top six forwards (maybe):
Boeser
!st rounder 2017
1st rounder 2018
Middle six forwards (established):
Eriksson
Middle six forwards (maybe):
Gaudette
Goldobin
Dahlen
Bottom six forwards (established):
Sutter
Granlund
Gaunce
Bottom six forwards (maybe):
Virtanen
Boucher
Lockwood
I don't agree with the categories just because its not very descriptive of their roles. Top 6/Middle 6 both covers the 2nd line so realistically you could argue players being on either list due to the description (or both). Take someone like Eriksson, he had been a 30 goal scorer (and multiple times > 20 goals, career high 36 goals, miltiple 70+ pt seasons) and top 60 in the league in scoring (plus he is a fine 2 way forward) so by definition, he would be top 6. That said, he also clearly isn't a top line player anymore and you could argue his scoring was in more of a supporting role so middle 6 argument. You can even argue bottom 6 with his production this year... (24 points in 65 games... which is worst than h is rookie year of 31 in 69).
Also another similar player, the last few years in Vrbata has proven 1 season doesn't mean a lot... Remember his first year with us he scored 31/32 for 63 points. Then the very next season he had a Eriksson like year in producyion (27 points). This year his production bounced back to 53 points. In short, the player's usage has a lot to do with their production (and WD has been horrible with that this year). So realistically i would more likely give Eriksson the benefit of the doubt than just assume he is no longer a top 6 player going forward.
I would actually break up the category into top line players (which is really what top 6 is referring to anyways). Middle 6 since 2/3rd line is hard to split up and players often move between those lines and 4th liners (i.e. players that likely will play less minutes).
1st line likely (Sedin possible replacement)
Horvat - There clearly isn't anyone who can replace Sedin's production but Horvat is the closest, he leads the team in points and most nights his line is by far the best line (regardless of who his wingers are)
1st line upside/hopeful:
Boeser - Limited sample size but he has the shot to be a 30 goal scorer and seems to play well with Horvat.
2017 1st round - Considering its likely going to being in the top 6, lots of potential options
2018 1st round - Deeper draft than 2017 so unless we make the playoffs, just as much potential as 2017
Middle 6
Baertschi - Has been great with Horvat but not as good without him... At the very least looks like a support player so he will be no worst than a top 9 forward
Eriksson - Moves up and down the line-up but is solid in his own end and past production would put him in top 60 (top 2 lines) so he's no worst than a 3rd liner
Shutter - Don't like his contract but he's a legitimate 3rd liner in the NHL. His production is align with most 3rd liners in the league (and note he didn't score much on the PP so its not like the Sedins/PP inflated his production) plus he played on the 3rd line for a cup contender in Pittsburgh. Still in the prime of his career so no reason to expect him to be anywhere but the middle 6.
Granlund - Produced pretty much what you expect a 3rd liner to produce... has offensive upside to be a 2nd liner but was no worst than a 3rd liner for us this sason
Middle 6 (high potential, as in likely will be a middle 6 forward)
Goldobin - Former 1st round pick, has a ton of offensive skills but not really being deployed well, his offensive ability gives him 2nd/3rd line potential
Gaudette - Solid 2 way game in NCAA and his scoring number is among the best ever for a 2nd year player (in the NCAA), think 'nucks fan might be surprised how good he is when he signs (think Boeser part 2)
Lockwood - Hansen comparison and considering the hype he's getting now, he'll likely be no worst than a 3rd line winger who moves up and down the top 9
Dahlen - PPG in Tier 1 SHL (1 level below the top) is very good for D+1 year...
Middle 6 (low potential, meaning more likely will be 4th liners)
Boucher - Shown flashes of offense and has a deadly shot... of course forgets how to play D every so often could hurt his chances... also someone who was waived a few times (but also claimed every time) shows both his upside and how he isn't there yet
Gaunce - He was a 4th liner, his upside suggest he might develop into a 3rd line center at best so potential is low but he also showed he could play in the NHL (at least) as a rookie.