I would bet that none of Kuokkanen, McLeod, Bastian, or possibly even Boqvist ever match what Johnsson did in 2018-19. Possibly not even what he did in 2019-20. Sharangovich might but the jury is still out.
McLeod is a center with very solid two-way ability, so I'd remove him from this argument. Bastian is not expected to be a 20-goal top 6 guy -- we're happy with him as a power 4th line winger with a bit of scoring pop and physicality, so we should probably take him out, too.
So this narrows down the question to:
can Kuokkanen or Boqvist become superior players to Johnsson?
Kuokkanen is a different player, for certain. He lacks Johnsson's shot and nose for the net, but he is far better at distributing the puck and anticipating the play. Statistically, Kuokkanen's final AHL season (at 22 years old) saw him score 48 points in 56 games. While Johnsson's final AHL season (at 24 years old) saw him score 54 points in 54 games. So, is the question -- can Kuokkanen ever hope to match Johnsson's accomplishment of 67 career points going into his 27-year old season? I'd say the idea of Kuokkanen having accumulated 68 career NHL points entering the 2025-26 campaign is not extremely far fetched.
As far as Boqvist.. well, to me this argument is flat out silly. Boqvist is faster, smarter, plays harder on and off the puck, is light years superior with passing, vision and anticipation, and has the ability to slot in at center or the wing. He creates chances, whereas Johnsson's job is to finish chances. I'm not going to get ahead of myself and say Boqvist is a can't miss top 6 stud, but I think most of us would be downright shocked if he did not have 68 career NHL points entering the 2025-26 campaign.
What Johnsson did in 2018-19 was certainly an accomplishment. He scored 20 goals -- not an easy thing to do -- acting as the finisher/net-crasher for Hall of Famers like Matthews and Tavares.
I'm not sure where the myths were created that 1) the Devils prospects and young players are not that good; and 2) that Andreas Johnsson's move to New Jersey was somehow going to give him the vision and anticipation to be a first-line caliber winger.
I'm not trying to insult the kid, or bemoan his trade acquisition. He's certainly an NHL-er who can contribute some offensive pop for your bottom 6, maybe play at the net front on your 2PP. He's a nice depth acquisition, and though he's certainly overpaid for what he brings, the Devils had the cap room and the prospect depth at RW to deal Joey Anderson and still be able to consider the position a major organizational strength.
But again, the ideas I'm reading that we should drop Sharangovich from the top line to "get Johnsson going" are ridiculous. You do not move depth players to your top line to "get them going". You "keep Jack Hughes going" by keeping him alongside the player he is excelling alongside.