Sure, Toronto could be a threat. But there are a lot of "if's" that have to go right for them.
* If Kawhi is fully healthy
* If Kawhi buys into the team culture there
* If Nurse is capable of getting more from the rest of the team in the playoffs than Casey was
* If Anunoby and Siakam take a step forward in their progression
* If Ibaka doesn't become completely useless
* If Danny Green doesn't see further slippage in his game
So, sure, if most or all of these things work out in their favor, they could be a threat. My guess is it doesn't work out as they hope and Kawhi leaves next summer.