While speculating with any potential NHL additions, you guys are kinda overlooking the fact that apart from GMH, we do already have the potential makings of a very good scoring line, even if zero NHLers show up. I'm talking of Aaltonen-Ojamäki, the Vityaz duo.
Now, they were not exactly a force in Beijing, as Ojamäki ended up watching the games from the pressbox after the opener vs. Slovakia - but it was a highly unusual situation, not by any means his own fault. Rather, it was an unfortunate effect of some musical chairs caused by some COVID scares. A couple of forwards got sidelined, which opened a way into the lineup for Nättinen and Komarov, and they capitalized on those chances. Furthermore, the Olympics were a very short tournament - only six (or seven) games, and by the time all the players were cleared, the tournament was already at its half-way mark, and Jalonen did have four somewhat functional lines in his hands, even though they didn't feature all the players he likely had penciled in initially. And so he decided to play it safe and keep running with what he had rather than risk it for potentially higher rewards.
But now, it's a whole different situation. There's a month-long training camp before the WHC with whopping ten games they can use to iron out any kinks in the lineup. So without a doubt the Vityaz boys will get another chance at showing what they can do. Which may very well lead to a top-six of:
Granlund-Manninen-Hartikainen
X-Aaltonen-Ojamäki
The X here would be some suitably skilled player - perhaps some lone NHLer (Maccelli, maybe Donskoi, even Laine if the hockey gods smile), or perhaps some high-profile European (Pesonen, Rajala), or even some surprise addition from Liiga, like Levtchi.
Furthermore, while usually the finals in Liiga and other top Euro leagues have been tricky schedulewise, not this time. We likely know all the champions before the month is over, and there are still not one, but two complete EHT legs to be played, starting at April 28th. So Jalonen can even give some interesting players an additional look, unlike the past few years, when any additions from the Liiga finals made it straight into the final roster.
One last thing - let's not forget that Aaltonen was pretty good in the olympics even without his counterpart, so it's quite likely he takes preference over some not-so-established overseas hopeful, like Maccelli or Ruotsalainen, anyway.