Mayfield is a really tricky case to project. There are so many factors up in the air or unclear.
1)Big RHD tend to get paid. Just look at the Gudbranson contract last summer. $4M x 4 for an inferior player. There are tons of teams searching for that "stabilizing" stay-at-home RHD. Question is...how do GMs generally view Mayfield? He doesn't have near the same pedigree as Gudbranson, or even a guy like Manson. Chiarot is another potential comparable, but with more "grit" and "pedigree" as well @ $4.75M.
2)He's the only guy on the market in his real "niche". None of Severson/Klingberg/Dumba really fit the same role as other RHD options. Scarcity can make goofy things happen.
3)He's going to be an old, 30 year old UFA. That makes the term even more complicated to predict. Compounded by the fact he's not what i would describe as the most stellar, effortless skater. How far into his declining mobility years are teams willing to go to land him for the short-term?
4)The salary cap as a whole is still very tight, with some ambiguity about where exactly it's headed.
5)Mayfield has played out his entire career thus far on "bargain deals". Is he going to take this opportunity to cash out and set himself and his family up for life? Or is he going to prioritize playing for a quality team and having a shot at winning? No idea where his head is at...but i could certainly understand if he wanted to chase the biggest payday possible with this contract.
My initial impression would be to expect something like $4-5M for 5 or 4 years, respectively. ~$20M ballpark. But i wouldn't really be shocked to something idiotic in excess of that if it truly turns into a "bidding war". I also wouldn't be shocked to see him re-sign with the Isles for like $3M for 6 years or something. Really could go a lot of ways.
Where the contract ends up will really impact how much interest i'd have in the Canucks pursuing him. No doubt he'd look good beside Hughes, especially compared to what we have as alternatives. But he has a really scary profile as a guy to tie yourself to for more than a few years at any sort of significant money. He's not a real "impact" player, he's on the older side, and not the most gifted skater. He's also played most of his career as a bottom-pairing, fringe Top-4D. Is that really a guy you can invest in to play on your top pair...or are you going to want to keep seeking out "better" options? Are you going to wish you'd just spent a couple million more per year on Severson or tried to find some other option entirely?
Really fascinating Free Agent though. Which means it'll probably end up in some really unremarkable re-signing with the Isles and much ado about nothing.