Swapping out Reinhart for Boeser really doesn't do much to help either side as both are RW's, and Boeser is younger and a little cheaper for a couple more years.
Virtanen would be borderline untouchable for Vancouiver with his style of play and is a kind of player teams covet during playoff time.
Mittelstadt would be a risk for Buffalo to trade and for Vancouver to take on. Vancouver would probably want Cozens instead

I don't think Vancouver would trade any of those core guys, they will look to move out some salary and if any, maybe a prospect or two to improve

you are probably right, for van strictly setting up for followiing year re-signing petterson/hughes. take a look at my van side of this , Buffaloed.