He's signed long term, our roster is only getting better, as is he, and there's no frustration or pain with him. He's said multiple times that he loves Arizona, wants to stay with us, and thinks we can have a good future. Just because his dad said otherwise on twitter doesn't make it so. Neither one of us knows what he's really thinking.
It's ridiculous that a 24yo 86 point per game player could possible be losing value when he's 27 and still signed long term. If he puts up 100 pts in the next 2 years you think his value is going to go down? That's asinine and insane. His value is very high right now and will continue to be so until 2 years before his contract is up most likely, if not later. Yeah he may break his back and never play again, but if you call up GMBA and say that you won't give him full value because of that you're going to be laughed at. The same is true of every player in the league. Does McDavid have less value because of that?
Players generally enter their prime around 26-28yo and Keller isn't particularly close to that point. He's signed extremely cheaply for a PPG player. If he puts up more than a ppg he may end up being one of the best deals in the league.
2 late 1sts and a bottom 4 defenseman is about the same value as Newhook, Chychrun, Ekholm, Jeannot, etc. There are some other similar deals like PLD and Meier, and the deal you're referring to is probably most similar to the Horvat one in recent memory, who was traded for a 1st, recent 1st round pick, and potentially decent-good player. When he was 28 with one year left after being a mostly not quite PPG player. Last time someone got 2 1sts straight up was Hagel last year.
So no, I don't think that's a good deal, and no I don't think his value will go down in the next 2 years.