There is no way you hold Matthews out 3 months to add additional players. Dude is the defending Hart trophy/best player in the league.
Have you looked at Karlsson's contract and injury history. He has caught lightning in a bottle as a 32 year old with 4 more years @ $11.5/season after this.
Then you want 29 year old Miller for 7 more years @ $8 million/season.
I guess you don't want to resign Auston or Willy...
If San Jose keeps 50% on Karlsson that cuts down the amount an if they want to move on from him then they could retain 50% of the remainder taking the cap trade hit down to 2.75 million. That has trade value.
A danger is that Arizona will be just coming into their window for a cup and have an insane number of draft picks, prospects and cap space.
They will be on the cusp of becoming a playoff and cup contender. IF they signed Mathews there he would attract other top notch FA's and there would be line ups to buy tickets, especially in that dinky tool rink but guess what the new huge rink will be completed in 3 years, just about the time for a Mathews signing to fill the arena.
I am sure if the brain trust thinks Mathews will move on they will look into trade options
Miller could be traded before his new contract is certified in September