A lot depends on what position your team is in right now. If you're in a position to compete for a title or some money this season, absolutely not. Heiskanen this season would be a downgrade from Werenski. Plus Werenski is already established and only in his third NHL season.
If you're rebuilding or have zero chance of winning your league championship this season, then I might consider it, since you have a number of solid young blueliners in your pipeline to choose from in the future.