You could give him a long term commitment but honestly that means nothing if the GM fears for their job or the board demands a blood sacrifice.
I would assume that any promises to Carle would be that the team is going to move in his direction (as in Chayka's on the same page) whether that is with Matthews at the helm or in a more conventional rebuild.
The appeal is always going to be money and the prestige of coaching the Leafs. It's either enough to entice him or it isn't.
I just hope whoever gets the job runs a play style that is worth watching. I can take losing. Hell we can finish dead last next year for all I care. As long as the team looks entertaining in defeat I can live with it. I can't take another season of being perpetually out chanced as a feature.
Chances to win is a big appeal too. Or the coach quickly fades onto the scrap heap of coaches who fell short.
The chances of Carle being able to win a Cup any time soon with this group are pretty small. Why would he come to Toronto over other situations clear of the Canadian tax code?
I'd prefer a rebuild. But they're not going to do that willingly. They want dangle hope to Matthews and get their playoff revenue.
Finding "a play style that is worth watching" is something I think that this current roster is capable of - playing better than what they attempted this past season with the talent they already have. Short term, Chayka could look clever and get them back into the playoffs. He still has a challenge in that the UFA market is going to be limited again and I'm reading the over/under on McMann's UFA deal, for example, is $6 mil !!! (good for him of course) - prices are going to be nuts with the large rise in the cap.
I think Rielly, who is still skating well, could be revived under "a play style that is worth watching" and his price tag of $7.5 mil isn't that bad compared to the UFA prices to come. The bidding on Raddysh will far exceed that. They need a right handed puck mover.
They have to flip one of Woll, Stolarz or Hildeby or lose one of them on waivers. They could get a 3/4 center back.
Then they could use the balance of the remaining cap space to boost the forwards defensive ability/two way play and depth.
Some others here, including yourself, probably have some better ideas.
That gives them a decent shot at the playoffs - far from guaranteed with the improvement in other teams in the East. But I think it will be more entertaining to watch ... until the déjà vu in the playoffs.