I could see Dallas wanting Petry retained, MTL wanting Askarov, and NSH wanting Klingberg signed.
That said you've got the values way off imo.
Also, not one person has made a logical argument to me why Nashville would ever need/want to acquire Weber. They can't force him to be on LTIR if he plans on retiring, so even in that unlikely scenario it doesn't make sense.
My version of this trade would look something like this:
Dallas gets: Petry retained, NSH 1st
Nashville gets: Klingberg signed, MTL 2nd
Montreal gets: Askarov
For Nashville:
The key being that MTL 2nd is just a small downgrade on the 1st they give up.
I'm not suggesting NSH wants to get rid of Askarov either, but they may see it worthwhile to get a signed Klingberg, while only slightly downgrading their pick.
For Dallas:
Their uncomfortable with Klingberg's ask, they get a guy in Petry who is clearly unhappy in Canada, and a strong contender for rebound at a cost controlled price for 3 years.
They also manage to snag an additional 1st in the draft. Something they can use either in an additional trade, or to build for the future.
For Montreal:
They need to move on from Petry now, despite his value being so low. It's gotten to the point where he's clearly very unhappy and it's only going to get worse.
They have a number of picks in the draft and giving up an early 2nd hurts, but they can recoup it by either packaging picks or moving a Lehkonen, Chiarot, etc. They will still be well positioned in the draft.
Getting Askarov provides some support for a position where the number of darts matter. Montreal has had the luxury of Price for so long now, they need one of their Goalie prospects to pan out. This significantly helps those chances.
So what do Nashville and Dallas fans think? I'm sure Montreal fans are hoping for more value for Petry, but I don't think it's there, even retained.