Ultimately most players, want to play in a place where they have a chance to win, have a good relationship with the coach and management, and a belief that the organization is headed in the right direction.
A huge number of players come from Ontario, approx 22% of the league with approx 60 coming from the GTA alone. Toronto had a poor franchise for a long time, poor management, and wasn't a real destination for anyone, no matter where they were born. Having said that, where he already is, should have a by far better season this coming season, and from a winning perspective, be far further in his development. I'd say the odds of a signing an Offer Sheet would be remotely small.
If Arizona, is still in Arizona, and they are a top team when Matthews does his subsequent contract, I could see it being an attractive franchise for him, if Toronto is no longer as competitive, or there is management/coaching issues. But that's some nine seasons from now, and plenty can change in the world, between now and then, so not much of a point in speculating.