The best scenario by far is that Irving breaks out next year and beasts from that LDE position.
Dallas may have leverage, I cant find the details of how much of his future salaries are guaranteed. If they can cut him, even without gaining cap room, they do have leverage because Crawford's value on the open market will become the baseline for a renegotiation. For example, if Crawford could only get 3 Million a year after being cut and Dallas offers him a renegotiation down to 4MM, he still comes out ahead.
That said, I don't know how much of his deal is guaranteed. If all of it is guaranteed, its all a moot point like you say.