I think Namestnikov is a more valuable player than he is getting paid for. Which he might get paid for as a result.
Instead of looking around the league for placeholders, maybe keep the one that is here, especially if you are trying to find the unicorn who makes Ehlers and Perfetti a dynamic secondary scoring line.
Organizationally you could postentially move from older players like Ehlers and Appleton into younger ones like Chbrikov and Lambert, or even Lucius or Yager. That's not as scary as it has been painted in the past, because the Jets have drafted forward heavy from 2020-2023
The need for a top 4 defenseman is insulated by the development of Salomonsson. I think the only people who have a real sense of his timeline are in the organization. That's where I'd look at placeholder though. Heinola is getting regular season minutes, but he might be on the outside looking in when it gets to heavier, battle testing playoff levels, in his first season with the team in a non prospect capacity. That right side still seems thin with Miller being somewhere between depth and starting. I like the idea of Fleury and De Melo as a 3rd pairing for playoff hockey, having a guy who can play more minutes with Morrissey and push the pace even higher would be my top priority at the deadline. C/RW depth, RH shot in a defensive/ PK capacity would be me second for me. A talented enough player to be able to fill in for Namestnikov at C, or Appleton at RW, if needed.
I'd still out throw a Dach and Justin Barron trade, with a draft pick for Ehlers. That would change the look of the Jets for the playoffs. And I still think Montreal is in the best position to re-sign Ehlers, given how much Laine is enjoying playing hockey again in Montreal. Ehlers could get the same kind of treatment if he pushed that team into the playoffs past the Bruins. Barron is expendable for the Habs, as Mailloux is going to get on that team sooner or later. And they still have a 5th OA pick on RD behind him.